It is a Thesis of B.Sc Civil by Suman Jyoti
info.sumn.ce@gmail.com
Dhaka University of Engineering and Technology, Gazipur
Thesis of numerical simulation of flow through open channel with series of Groins
The document discusses the impacts of large dams on the environment and climate, using the Tehri Dam in Uttarakhand, India as a case study. It summarizes that the Tehri Dam provides benefits like hydroelectric power, flood control, irrigation, and tourism, but also resulted in mass displacement of people, deforestation, and impacts on biodiversity. Mitigation efforts were undertaken for afforestation, erosion control, and protecting displaced communities and the environment.
The document discusses structural and non-structural measures for reducing risks from different natural hazards like cyclones, droughts, earthquakes, and floods. Structural measures involve physical construction to mitigate hazards, while non-structural measures do not involve construction and instead use practices, policies, and public awareness. Examples of both structural and non-structural measures are provided for each hazard.
Final year project proposal on feasibility study of small hydro powersurya paudel
This document is a proposal for a final year project on conducting a prefeasibility study of the Katti Khola small hydropower plant in Dailekh, Nepal. It was submitted by five students to the Hydro Power Instruction Committee at Mid Western University. The proposal outlines the objectives, methodology, expected outcomes, budget and timeline for the project. It involves surveying the site, collecting hydrological and geological data, designing the plant components, estimating costs and drafting a final report. The study will evaluate developing the site as a run-of-river plant with an estimated capacity of 2.978 MW utilizing a head of 100m and flow of 4 cumecs. The proposal provides details on the site location, literature
The document discusses various elements of a water conductor system for hydropower projects. It describes intake structures, including trash racks and gates. It discusses open channels like canals and pressure tunnels. It provides details on penstocks, including types (buried vs exposed), design considerations, and factors for determining alignment. The key components discussed are intake, head race tunnel, surge tank, penstock, and their functions in conveying water from the source to the hydropower plant turbines.
This document provides an outline for a presentation on evaluating the performance of desilting basins used in small hydropower plants. It discusses the problems caused by sediment in SHP plants and how desilting basins are used to trap sediment before it reaches turbines. The objective of the study is to evaluate the performance of existing desilting devices and examine the impact of sediment on turbines. Data was collected from 14 SHP sites through site visits. Desilting basin efficiency was evaluated using various methods and compared to observed efficiency. Analysis found the effect of desilting basin efficiency on turbine runners.
El documento presenta información sobre aliviaderos, incluyendo sus antecedentes históricos, clasificaciones, componentes, diseño hidráulico y estructural, y ejemplos. Aborda el estudio inicial de aliviaderos realizado por George Fetter Stickney en 1922, y menciona diferentes tipos de clasificaciones de aliviaderos como por su posición, ubicación, tipo de conducción y vertimiento. Explica los componentes típicos de un aliviadero y el diseño hidráulico de un aliviadero de cimacio.
El documento presenta fórmulas y conceptos relacionados con el cálculo de energía en canales de fluidos. Explica que la energía específica en una sección de un canal depende de la profundidad, la pendiente y la gravedad. También presenta ecuaciones para calcular la energía total, la velocidad del fluido y el caudal, usando conceptos como la pendiente, el coeficiente de Manning y el coeficiente de Chézy.
The document discusses the impacts of large dams on the environment and climate, using the Tehri Dam in Uttarakhand, India as a case study. It summarizes that the Tehri Dam provides benefits like hydroelectric power, flood control, irrigation, and tourism, but also resulted in mass displacement of people, deforestation, and impacts on biodiversity. Mitigation efforts were undertaken for afforestation, erosion control, and protecting displaced communities and the environment.
The document discusses structural and non-structural measures for reducing risks from different natural hazards like cyclones, droughts, earthquakes, and floods. Structural measures involve physical construction to mitigate hazards, while non-structural measures do not involve construction and instead use practices, policies, and public awareness. Examples of both structural and non-structural measures are provided for each hazard.
Final year project proposal on feasibility study of small hydro powersurya paudel
This document is a proposal for a final year project on conducting a prefeasibility study of the Katti Khola small hydropower plant in Dailekh, Nepal. It was submitted by five students to the Hydro Power Instruction Committee at Mid Western University. The proposal outlines the objectives, methodology, expected outcomes, budget and timeline for the project. It involves surveying the site, collecting hydrological and geological data, designing the plant components, estimating costs and drafting a final report. The study will evaluate developing the site as a run-of-river plant with an estimated capacity of 2.978 MW utilizing a head of 100m and flow of 4 cumecs. The proposal provides details on the site location, literature
The document discusses various elements of a water conductor system for hydropower projects. It describes intake structures, including trash racks and gates. It discusses open channels like canals and pressure tunnels. It provides details on penstocks, including types (buried vs exposed), design considerations, and factors for determining alignment. The key components discussed are intake, head race tunnel, surge tank, penstock, and their functions in conveying water from the source to the hydropower plant turbines.
This document provides an outline for a presentation on evaluating the performance of desilting basins used in small hydropower plants. It discusses the problems caused by sediment in SHP plants and how desilting basins are used to trap sediment before it reaches turbines. The objective of the study is to evaluate the performance of existing desilting devices and examine the impact of sediment on turbines. Data was collected from 14 SHP sites through site visits. Desilting basin efficiency was evaluated using various methods and compared to observed efficiency. Analysis found the effect of desilting basin efficiency on turbine runners.
El documento presenta información sobre aliviaderos, incluyendo sus antecedentes históricos, clasificaciones, componentes, diseño hidráulico y estructural, y ejemplos. Aborda el estudio inicial de aliviaderos realizado por George Fetter Stickney en 1922, y menciona diferentes tipos de clasificaciones de aliviaderos como por su posición, ubicación, tipo de conducción y vertimiento. Explica los componentes típicos de un aliviadero y el diseño hidráulico de un aliviadero de cimacio.
El documento presenta fórmulas y conceptos relacionados con el cálculo de energía en canales de fluidos. Explica que la energía específica en una sección de un canal depende de la profundidad, la pendiente y la gravedad. También presenta ecuaciones para calcular la energía total, la velocidad del fluido y el caudal, usando conceptos como la pendiente, el coeficiente de Manning y el coeficiente de Chézy.
Hydraulic tunnels are underground water conduits that convey water without disturbing the surface. They have several advantages over surface canals, including less environmental impact, shorter routes, and not disturbing the natural landscape. However, they have higher construction costs and risks. Tunnels can be circular, D-shaped, or horseshoe-shaped depending on rock conditions. They require lining after excavation to increase strength and hydraulic capacity. Common excavation methods include drilling and blasting, tunnel boring machines, and the New Austrian Tunneling Method. Proper support like rock bolts and steel ribs is needed to prevent tunnel collapse.
This document provides information about hydroelectric power plants. It discusses the basic components and principles of hydroelectric dams, including reservoirs, dams, penstocks, turbines, generators, and transformers. It also describes different types of hydroelectric plants based on factors like head, capacity, and location. Several major hydroelectric plants in India are discussed as examples, including Sardar Sarovar and Ukai. International examples of different types of dam structures are also summarized.
This document summarizes the requirements for preliminary design of a new sewage pump station. It includes conducting geotechnical investigations, surveying the site, and performing an environmental assessment. The geotechnical investigation involves drilling borings and preparing a report with soil properties. The survey establishes horizontal and vertical site controls. An environmental site assessment evaluates potential soil and groundwater impacts. These preliminary design activities provide information to evaluate the site and develop facility alternatives.
Este documento presenta conceptos básicos sobre hidráulica de ríos y modelización con HEC-RAS, incluyendo régimen de flujo mixto, tipos de perfiles, obtención del calado crítico, condiciones de contorno, definición de secciones transversales y distancias entre ellas.
This document lists 47 water resource engineering projects available for students in BE/B.Tech and ME/M.Tech programs through Sree Samarth Project Solution located in Aurangabad, India. The projects cover a wide range of topics including groundwater inventory, water treatment, water quality analysis, rainwater harvesting, wastewater recycling and more. Contact is provided for Lakade Sagar at the listed phone number and email for more details on the available projects.
The document provides an overview of open channel hydraulics and discharge measuring structures. It discusses:
- Uniform and non-uniform open channel flow conditions, including gradually varied, rapidly varied, subcritical, critical and supercritical flows.
- Basic equations for uniform flow such as the continuity, energy and momentum equations.
- Hydraulic principles and formulas used to design channels and structures, including the Chezy and Manning's equations.
- Characteristics of gradually varied flow and methods for analyzing water surface profiles.
- Phenomena such as flow over a hump, through a contraction, and hydraulic jumps; and equations for analyzing conjugate depths.
1) Hydroelectric power plants utilize the potential and kinetic energy of flowing water to generate electricity. Water is collected in a reservoir behind a dam and then sent through turbines connected to generators.
2) The essential components of a hydroelectric power plant are the catchment area, reservoir, dam, penstocks, turbines, generators, and tailrace. Water is stored in the reservoir and released through penstocks to spin the turbines.
3) Dams can be classified as masonry dams, which include gravity, buttress, and arch dams, or fill dams, consisting of earth-fill or rock-fill structures. Spillways help regulate reservoir levels and provide a safe passage for excess water.
This document provides information on small hydro power plants, including their essential elements and working. It discusses that small hydro power plants can utilize small rivers and streams with little environmental impact. The key elements are a catchment area, reservoir, dam, turbines, draft tubes, power house, and safety devices. It explains that water is stored in the reservoir and flows through penstocks to drive the turbines and generate electricity in the power house. Some advantages are low costs and emissions while disadvantages include high initial costs and dependence on water availability.
Water accounting can be defined as the systematic study of the current status and future trends in water supply, demand, accessibility and use within a specified spatial domain. The concept of water accounting is based on the argument that knowledge of the current status of water resources, the capacity and condition of water supply infrastructure and trends in water demand and use is a precondition for successful water management, Land and Water Days in Near East & North Africa, 15-18 December 2013, Amman, Jordan
This presentation summarizes key aspects of hydroelectric power plants. It introduces hydroelectricity as a renewable energy source that converts the kinetic energy of flowing water into electricity. It then discusses applications of hydroelectric power, providing examples of how hydroelectric plants can supply base load and peak load power. The document proceeds to describe the Kaptai hydroelectric power plant in Bangladesh as a case study, detailing its dam, reservoir, and power generation capacity. It concludes by outlining the essential components and schematic arrangement of typical hydroelectric power stations.
Water flowing over a spillway acquires a lot of kinetic energy because of the conversio of the potential energy into kinetic energy.
If the water flowing with such a high velocity is discharged into the river it will scour the river bed.
If the scour is not properly controlled it may extend backward and may endanger the spillway and the dam.
The document describes the design of a forebay for a hydropower system. It begins by outlining the key components and functions of a forebay. It then provides design guidelines and parameters to consider, such as volume, depth, width, and spillway size. Two design examples are presented. The first designs a forebay with a discharge of 2 cubic meters per second and the second designs one with a discharge of 12 cubic meters per second conveyed by two penstocks. Both examples calculate the necessary dimensions and design characteristics of the forebay based on the given parameters.
This document presents information about artificial groundwater recharge by Ankit Saini. It discusses the need for artificial recharge due to increasing water demand and declining groundwater levels. It describes various methods of artificial recharge including surface methods like flooding, basin tanks and sub-surface methods like recharge wells, shafts and dug wells. The document emphasizes that artificial recharge helps augment groundwater storage but sustained management is also needed.
The document discusses earthen dams. Earthen dams are constructed of materials like clay, sand, and gravel when the foundation is too weak to support a masonry dam or competent rock is at a great depth, making earthen dams a low-cost option. They have a trapezoidal shape and are relatively lower but broader at the base compared to other dam types. A typical earthen dam layout includes components like the heel, crest, toe, and spillway. There are three main types of earthen dams: homogenous, zoned, and diaphragm. Earthen dams are used for water supply, drought/flood control, irrigation, recreation, navigation, fisheries,
This document discusses hydropower resources and potentials for renewable electricity in Nigeria. It provides an overview of small hydropower systems, including their advantages such as being environmentally friendly and having relatively low operational costs. Estimates indicate Nigeria has over 700MW of potential from small hydro sites. A case study of a 3kW run-of-the-river hydropower scheme in a rural Nigerian village demonstrates how local communities can develop small hydropower to provide electricity using locally available materials and skills at low cost. The scheme improved villagers' quality of life. Overall, the document promotes small hydropower as a way to decentralized renewable energy access in Nigeria.
This document discusses constraints and load flow analysis in power systems. It outlines four key constraints: active power constraint, reactive power constraint, voltage magnitude constraint, and load angle constraint. It also describes load flow analysis as a balanced mechanism between demand and generation under incremental loading. Load flow analysis is important for the safe and future operation of power systems. The document further discusses bus classification, basic power flow conditions including the proportional relationships between reactive power and voltage and active power and load angle. It also covers the development of the Y-bus matrix considering line resistances and inductances alone and then including line capacitances.
1) Water conveyance systems include open channels and pressure flow systems. Open channels include natural rivers and streams as well as artificial canals and flumes.
2) Intake structures are used to obtain water from sources like rivers, reservoirs, and lakes for hydroelectric power or irrigation. Intakes include trash racks, screens, and gates to control water flow.
3) Forebays are pools of water located before penstocks that distribute and store water for hydropower plants. They contain trash racks to prevent debris from entering the penstock.
Lec-10-Week (7)( Hydraulics of water Distribution System).pdfKkkhanHan
The document discusses the design of water distribution systems. It states that the design must satisfy water needs and minimum residual pressure at all points. It discusses pressures, velocities, and the Hazen-Williams equation for calculating head loss in pipes. Hardy's Cross Method for designing pipe networks is also explained, with the basic principle being that the sum of inflows equals outflows at nodes and the sum of head losses around loops must be zero. Steps of the Hardy's Cross Method procedure are provided.
The document discusses numerical simulation of flow through an open channel with a series of groins. It presents the methodology used, which involves simulating flow fields using the 2D numerical model iRIC Nays2DH. Simulation is conducted for series of impermeable, permeable and combined groins placed in a straight channel. The velocity profiles, streamlines and velocity magnitudes around the different groin configurations are compared. The results show that combined groins influence favorable flow fields compared to impermeable and permeable groins alone.
This document is a dissertation submitted by Hea Yih Torng in partial fulfillment of a Bachelor of Engineering degree. The dissertation investigates the on-bottom stability of non-metallic submarine pipelines due to hydrodynamic loadings. Finite element analysis is used to determine the minimum weight of chain per unit length required to stabilize a non-metallic pipeline based on environmental conditions in the South China Sea. Hydrodynamic forces are calculated from wave and current data and applied to a pipeline model in ABAQUS to determine displacements.
Hydraulic tunnels are underground water conduits that convey water without disturbing the surface. They have several advantages over surface canals, including less environmental impact, shorter routes, and not disturbing the natural landscape. However, they have higher construction costs and risks. Tunnels can be circular, D-shaped, or horseshoe-shaped depending on rock conditions. They require lining after excavation to increase strength and hydraulic capacity. Common excavation methods include drilling and blasting, tunnel boring machines, and the New Austrian Tunneling Method. Proper support like rock bolts and steel ribs is needed to prevent tunnel collapse.
This document provides information about hydroelectric power plants. It discusses the basic components and principles of hydroelectric dams, including reservoirs, dams, penstocks, turbines, generators, and transformers. It also describes different types of hydroelectric plants based on factors like head, capacity, and location. Several major hydroelectric plants in India are discussed as examples, including Sardar Sarovar and Ukai. International examples of different types of dam structures are also summarized.
This document summarizes the requirements for preliminary design of a new sewage pump station. It includes conducting geotechnical investigations, surveying the site, and performing an environmental assessment. The geotechnical investigation involves drilling borings and preparing a report with soil properties. The survey establishes horizontal and vertical site controls. An environmental site assessment evaluates potential soil and groundwater impacts. These preliminary design activities provide information to evaluate the site and develop facility alternatives.
Este documento presenta conceptos básicos sobre hidráulica de ríos y modelización con HEC-RAS, incluyendo régimen de flujo mixto, tipos de perfiles, obtención del calado crítico, condiciones de contorno, definición de secciones transversales y distancias entre ellas.
This document lists 47 water resource engineering projects available for students in BE/B.Tech and ME/M.Tech programs through Sree Samarth Project Solution located in Aurangabad, India. The projects cover a wide range of topics including groundwater inventory, water treatment, water quality analysis, rainwater harvesting, wastewater recycling and more. Contact is provided for Lakade Sagar at the listed phone number and email for more details on the available projects.
The document provides an overview of open channel hydraulics and discharge measuring structures. It discusses:
- Uniform and non-uniform open channel flow conditions, including gradually varied, rapidly varied, subcritical, critical and supercritical flows.
- Basic equations for uniform flow such as the continuity, energy and momentum equations.
- Hydraulic principles and formulas used to design channels and structures, including the Chezy and Manning's equations.
- Characteristics of gradually varied flow and methods for analyzing water surface profiles.
- Phenomena such as flow over a hump, through a contraction, and hydraulic jumps; and equations for analyzing conjugate depths.
1) Hydroelectric power plants utilize the potential and kinetic energy of flowing water to generate electricity. Water is collected in a reservoir behind a dam and then sent through turbines connected to generators.
2) The essential components of a hydroelectric power plant are the catchment area, reservoir, dam, penstocks, turbines, generators, and tailrace. Water is stored in the reservoir and released through penstocks to spin the turbines.
3) Dams can be classified as masonry dams, which include gravity, buttress, and arch dams, or fill dams, consisting of earth-fill or rock-fill structures. Spillways help regulate reservoir levels and provide a safe passage for excess water.
This document provides information on small hydro power plants, including their essential elements and working. It discusses that small hydro power plants can utilize small rivers and streams with little environmental impact. The key elements are a catchment area, reservoir, dam, turbines, draft tubes, power house, and safety devices. It explains that water is stored in the reservoir and flows through penstocks to drive the turbines and generate electricity in the power house. Some advantages are low costs and emissions while disadvantages include high initial costs and dependence on water availability.
Water accounting can be defined as the systematic study of the current status and future trends in water supply, demand, accessibility and use within a specified spatial domain. The concept of water accounting is based on the argument that knowledge of the current status of water resources, the capacity and condition of water supply infrastructure and trends in water demand and use is a precondition for successful water management, Land and Water Days in Near East & North Africa, 15-18 December 2013, Amman, Jordan
This presentation summarizes key aspects of hydroelectric power plants. It introduces hydroelectricity as a renewable energy source that converts the kinetic energy of flowing water into electricity. It then discusses applications of hydroelectric power, providing examples of how hydroelectric plants can supply base load and peak load power. The document proceeds to describe the Kaptai hydroelectric power plant in Bangladesh as a case study, detailing its dam, reservoir, and power generation capacity. It concludes by outlining the essential components and schematic arrangement of typical hydroelectric power stations.
Water flowing over a spillway acquires a lot of kinetic energy because of the conversio of the potential energy into kinetic energy.
If the water flowing with such a high velocity is discharged into the river it will scour the river bed.
If the scour is not properly controlled it may extend backward and may endanger the spillway and the dam.
The document describes the design of a forebay for a hydropower system. It begins by outlining the key components and functions of a forebay. It then provides design guidelines and parameters to consider, such as volume, depth, width, and spillway size. Two design examples are presented. The first designs a forebay with a discharge of 2 cubic meters per second and the second designs one with a discharge of 12 cubic meters per second conveyed by two penstocks. Both examples calculate the necessary dimensions and design characteristics of the forebay based on the given parameters.
This document presents information about artificial groundwater recharge by Ankit Saini. It discusses the need for artificial recharge due to increasing water demand and declining groundwater levels. It describes various methods of artificial recharge including surface methods like flooding, basin tanks and sub-surface methods like recharge wells, shafts and dug wells. The document emphasizes that artificial recharge helps augment groundwater storage but sustained management is also needed.
The document discusses earthen dams. Earthen dams are constructed of materials like clay, sand, and gravel when the foundation is too weak to support a masonry dam or competent rock is at a great depth, making earthen dams a low-cost option. They have a trapezoidal shape and are relatively lower but broader at the base compared to other dam types. A typical earthen dam layout includes components like the heel, crest, toe, and spillway. There are three main types of earthen dams: homogenous, zoned, and diaphragm. Earthen dams are used for water supply, drought/flood control, irrigation, recreation, navigation, fisheries,
This document discusses hydropower resources and potentials for renewable electricity in Nigeria. It provides an overview of small hydropower systems, including their advantages such as being environmentally friendly and having relatively low operational costs. Estimates indicate Nigeria has over 700MW of potential from small hydro sites. A case study of a 3kW run-of-the-river hydropower scheme in a rural Nigerian village demonstrates how local communities can develop small hydropower to provide electricity using locally available materials and skills at low cost. The scheme improved villagers' quality of life. Overall, the document promotes small hydropower as a way to decentralized renewable energy access in Nigeria.
This document discusses constraints and load flow analysis in power systems. It outlines four key constraints: active power constraint, reactive power constraint, voltage magnitude constraint, and load angle constraint. It also describes load flow analysis as a balanced mechanism between demand and generation under incremental loading. Load flow analysis is important for the safe and future operation of power systems. The document further discusses bus classification, basic power flow conditions including the proportional relationships between reactive power and voltage and active power and load angle. It also covers the development of the Y-bus matrix considering line resistances and inductances alone and then including line capacitances.
1) Water conveyance systems include open channels and pressure flow systems. Open channels include natural rivers and streams as well as artificial canals and flumes.
2) Intake structures are used to obtain water from sources like rivers, reservoirs, and lakes for hydroelectric power or irrigation. Intakes include trash racks, screens, and gates to control water flow.
3) Forebays are pools of water located before penstocks that distribute and store water for hydropower plants. They contain trash racks to prevent debris from entering the penstock.
Lec-10-Week (7)( Hydraulics of water Distribution System).pdfKkkhanHan
The document discusses the design of water distribution systems. It states that the design must satisfy water needs and minimum residual pressure at all points. It discusses pressures, velocities, and the Hazen-Williams equation for calculating head loss in pipes. Hardy's Cross Method for designing pipe networks is also explained, with the basic principle being that the sum of inflows equals outflows at nodes and the sum of head losses around loops must be zero. Steps of the Hardy's Cross Method procedure are provided.
The document discusses numerical simulation of flow through an open channel with a series of groins. It presents the methodology used, which involves simulating flow fields using the 2D numerical model iRIC Nays2DH. Simulation is conducted for series of impermeable, permeable and combined groins placed in a straight channel. The velocity profiles, streamlines and velocity magnitudes around the different groin configurations are compared. The results show that combined groins influence favorable flow fields compared to impermeable and permeable groins alone.
This document is a dissertation submitted by Hea Yih Torng in partial fulfillment of a Bachelor of Engineering degree. The dissertation investigates the on-bottom stability of non-metallic submarine pipelines due to hydrodynamic loadings. Finite element analysis is used to determine the minimum weight of chain per unit length required to stabilize a non-metallic pipeline based on environmental conditions in the South China Sea. Hydrodynamic forces are calculated from wave and current data and applied to a pipeline model in ABAQUS to determine displacements.
This document provides background information on the durability of reinforced concrete structures in a saline environment. It discusses the deterioration mechanisms that can affect concrete, including corrosion of steel reinforcement due to chloride ingress. The document also reviews literature on measuring corrosion rates in steel sheet pile walls in a marine environment. It describes the methodology used for multi-phase modelling of ionic transport in concrete under externally applied current density using COMSOL Multiphysics software. The results and discussions section analyzes the simulation results, including the role of ion movement and concentration distribution profiles for different current densities. Comparison of 2D line graphs is also provided to analyze the influence of parameters like aggregate volume fraction and tortuosity on ion transport. The conclusion recommends this study
The document is a seminar report submitted by Mr. Unmesh Hanamshet on the topic of wireless transfer of electricity. It provides an overview of wireless power transmission technologies, including near field techniques such as inductive coupling and resonance inductive coupling, as well as far field techniques like microwave power transmission and laser transmission. The report discusses early pioneers in wireless power like Nikola Tesla and contributions from researchers like William Brown and Marin Soljacic. It also outlines some of the advantages, disadvantages and challenges of wireless power transmission.
This document provides an overview of rating curves, which relate water stage to discharge in open channels. It discusses the measurement of stage and discharge, different types of rating curves, factors that affect rating curves, and extrapolation techniques. The key points are:
1. Stage is measured using staff gauges, sensors, or other devices, while discharge is typically measured using current meters, weirs, flumes or other hydraulic structures.
2. Rating curves can be developed for steady, uniform flow or non-steady, non-uniform flow. Factors like vegetation growth, sedimentation, and variable backwater can impact the curve.
3. Extrapolation is often needed to estimate peak or low discharges beyond
This document summarizes Harsh Ranjan's internship report on fluid flow simulations conducted in curved pipes at the University of Manchester from May to July 2014. Ranjan investigated multiple solutions in curved-pipe flow, including the primary two-vortex solution and bifurcations to additional solutions. Parameters like wall shear stresses, vorticity, and stream functions were computed for different curvature ratios and Dean numbers. Additionally, a four-vortex solution was explored for a circular cross-section. The internship aimed to further understand fluid dynamics in curved pipes and potential applications to areas like blood flow in arteries.
This document discusses a thesis submitted by Sujay Kumar Patar for the degree of Master of Technology in Mechanical Engineering. The thesis studies turbulence in 2D magnetohydrodynamic flow over a square rib in an open channel using ANSYS Fluent software. It provides background on open channel flow, uniform and non-uniform flow, Reynolds averaged Navier-Stokes modeling, Reynolds stress distribution, velocity profiles in boundary layers, and flow characteristics such as laminar and turbulent flow. The objective is to analyze the effect of a magnetic field on flow using numerical simulation without physical experimentation.
The document is a thesis report submitted by Ng Jun Jie to the Department of Mechanical Engineering at the National University of Singapore in partial fulfillment of the requirements for a Bachelor of Engineering degree. The report analyzes and aims to improve the jacking systems used for lifting offshore jack-up rigs by studying the fatigue life of the rack and pinion mechanism and proposing ways to reduce stress through modeling and simulation.
This project report summarizes the analysis and design of an underground drainage system for the hostel areas of SRM University in Kattankulathur, India. The report outlines the objectives, necessity, scope and methodology of the project. It involves surveying the existing drainage system, analyzing wastewater and stormwater flows, selecting appropriate pipe materials, and designing the pipe network layout, trenches, manholes and cost estimate. The aim is to provide a systematic underground sewerage system to replace the existing open channel drainage and improve sanitation, flooding prevention and environmental protection on campus.
This dissertation submitted by Alejandro Marín Tamayo investigates the dynamic behavior of shallow water pipelines due to seabed liquefaction through numerical modeling. The study assesses how pipelines of varying diameters respond under different water depths when segments of the seabed liquefy and lose their ability to support the pipeline. The analysis considers wave-induced stresses on the seabed both with and without accounting for the dynamic response of the liquefied seabed. The results show that the structural behavior of lighter pipelines is more sensitive to the dynamic seabed response, whereas heavier pipelines are governed more by their own structural behavior when the seabed liquefies.
This document summarizes Daniel Melendy's master's thesis on modelling on-chip spiral inductors for silicon RFICs. The thesis addresses the need for scalable and predictive models of spiral inductors on lossy silicon substrates. It develops an enhanced Partial Element Equivalent Circuit (PEEC) method that includes the major non-ideal effects such as conductor and substrate losses. It also presents a new wide-band compact equivalent circuit model using "transformer-loops" to model substrate losses. Results comparing the models to measurements of octagonal spiral inductors on high-loss and low-loss silicon substrates show good agreement. The combination of an accurate scalable model and a wide-band compact model provides a complete modelling methodology for spiral
This document summarizes a thesis that models stormwater infiltration in roadside swales. The model routes flow over a fraction of the swale slope using a "fractionally wetted area" parameter, rather than assuming sheet flow. It uses the Green-Ampt infiltration equation and numerical solutions of overland flow equations. The model was developed in Matlab and its results were compared to three flume studies and a field experiment, showing the model's accuracy is limited by soil parameter inputs.
Review of Groundwater Surfacewater Interaction Modelling Sofware Approaches ...eWater
This report presents the outcomes of a review of the available approaches for modelling groundwater–surfacewater interactions at various spatial and temporal scales with different levels of complexity. It is aimed at determining the deficiencies of the current water modelling approaches for Australian conditions and making recommendations for future model development.
Modelling Analysis and Design of Self Anchored Suspension BridgeRohit Grandhi, EIT
The application of earlier course works in this project is summarized in Table 1.2:
Table 1.2 Application of earlier course work
Course Work Application in Project
Structural Analysis Analysis of loads, stresses and deformations of structural elements.
Structural Design Design of deck slab, girder, cables, suspenders as per codes.
Concrete Technology Design of M25 grade concrete mix.
Steel Structures Design of reinforcement details.
Geotechnical Engineering Foundation design not included in scope.
The document describes numerical simulation of transonic flow over a 3D wing. It discusses modeling a scaled down version of the ONERA M6 wing in Solidworks based on experimental data. Key specifications of the original and modeled wing such as chord lengths, sweep angles, and airfoil properties are compared. The Solidworks model is then imported into ANSYS for meshing and simulation using the Spalart-Allmaras turbulence model. Results will be analyzed for lift, drag, and pressure and compared to published experimental data to validate the simulation.
The document is a dissertation submitted by Mahato Lipika for the degree of Master of Science in Computer Control and Automation in 2016. It discusses leak location detection in gas pipeline networks. Chapter 1 introduces the background of gas pipeline networks in Singapore and the motivation for leak detection. The objective is to analyze pressure profile data using different methods to locate leaks in the network. Chapter 2 reviews literature on gas pipeline networks, leak detection techniques, and computational fluid dynamics modeling. Chapter 3 describes initial calculations, experiments conducted to collect pressure profile data from a test network setup under different leak conditions. Chapter 4 presents results of analyzing the data using various methods to locate leaks. Chapter 5 provides conclusions and suggestions for future work.
SAIL VERSUS HULL FORM PARAMETER CONFLICTS IN YACHT DESIGNBoyang Wang
The document describes a student project that aims to analyze the influence of sail and hull form parameters on yacht performance. It will generate a series of hull forms by modifying parameters of an initial YD-40 hull. Resistance and stability of the hulls will be calculated and their performance tested using sailing simulation software for different sail configurations. The document reviews methods for hull form modification, section mapping, resistance prediction, and stability analysis that will be used in the project.
This dissertation by Harsh Pandey investigates the manipulation and separation of objects at the microscale using simulations and microfluidic experiments. The document includes 7 chapters that cover: 1) developing a coarse-grained model to simulate the conformation-dependent electrophoretic mobility of polymers, 2) using the model to simulate the trapping and manipulation of deformable objects in microfluidic devices, 3) simulating the trapping of rigid objects using electric and flow fields, 4) microfluidic experiments observing the behavior of particles under flow and electric fields, 5) simulating the self-assembly of polymers at liquid interfaces, and 6) conclusions and potential future directions. The overall goal is to better understand and
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info.sumn.ce
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Suman Jyoti
Dhaka university of Engineering and Technology
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A thesis of numerical simulation of flow through open channel with series of groins by suman jyoti
1. NUMERICAL SIMULATION OF FLOW
THROUGH OPEN CHANNEL WITH
SERIES OF GROINS
A THESIS BY:
SUMAN JYOTI
Student ID: 191125
(info.sumn.ce@gmail.com)
In Co-operation with
MD. SONET KHAN AND SHWAON PAUL
Supervised By:
Prof. Dr. Md. Alauddin
Department of Civil Engineering
Submitted to the
DEPARTMENT OF CIVIL ENGINEERING
DHAKA UNIVERSITY OF ENGINEERING AND
TECHNOLOGY, GAZIPUR
2. i
Project Report Series 2021
In partial fulfillment of the requirements for the award of the degree
of
BACHELOR OF SCIENCE IN CIVIL ENGINEERING
APRIL, 2021
This series is published by
Bachelor of Science in Engineering Project Report
Department of Civil Engineering
Dhaka University of Engineering and Technology, Gazipur
The conclusion and viewpoints presented in this study are those of the
authors and do not necessarily coincide with those of the department.
Supervisor
DUET, 2021
3. ii
ABSTRACT
Rivers in Bangladesh are highly unstable due to their loose boundaries, mild slope at
bed and water surface, irregular siltation of huge sediment load coming from upstream,
and so on. Groins are installed in river bank in order to deflect the flowing water away
from vulnerable zone. In many cases, conventional groins are not functioning
successfully. The effect of groins with different configurations needs to be intensively
studied to defend the river bank from erosion, improve navigation, enrich the
biodiversity of aquatic species, and so on. The main objective of this study is to simulate
flow through open channel with series of groin models by using 2D numerical model,
iRIC Nays2DH. In this numerical simulation, K-ε model for turbulence and Cubic
Interpolation Pseudo-particle (CIP) method for advective terms are utilized. Simulation
of flow fields due to interaction of series of impermeable, permeable and combined
groins placed in a straight channel has been made. A given flow condition is applied
for all the groins. The simulation results depict that combined groins in series influence
favorable flow fields compared to impermeable and fully permeable groins. This causes
still water zone near bank at the downstream of impermeable part, then slow flow
through the permeable part. No strong circulation of flow at groin field and strong
current after the groin head is present.
4. iii
ACKNOWLEDGEMENT
All praises go to almighty Allah, the most magnificent merciful. The author gratefully
acknowledge their profound gratitude and indebtedness to project supervisor, professor
Dr. Mohammed Alauddin, Department of Civil Engineering, Dhaka University of
Engineering and Technology (DUET), Gazipur for his keen interest in this project,
continuous supervision, guidance, encouragement, inspiration and thoughtful
suggestion in completing the work.
The authors also grateful to honorable Head of the Department of Civil Engineering,
Professor Dr. Md. Kamal Hossain.
Finally authors would like to express gratitude to all the faculty members of the
Department for their kind Co-operation.
Authors
5. iv
NOTATIONS
ρ Density
u Velocity in the x direction
h Water depth
τx Riverbed shearing force in the x direction
τy Riverbed shearing force in the y direction
Fx Resistance by vegetation in the x direction
Fy Resistance by vegetation in the y direction
Cf Riverbed shear coefficient.
Cd Drag coefficient of vegetation.
l Length
Cμ Model constant
C1ε, C2ε, σk and σε K-ε model constants
n Manning's roughness parameter
L Length of channel
Q0 Discharge
h0 Mean depth
S Bottom slope
n Manning’s coefficient
u0 Mean velocity
6. v
LIST OF FIGURES
Fig. 2. 1 Finite difference grid.......................................................................................7
Fig. 2. 2 Conceptual relationship between consistency, stability and convergence......8
Fig. 2. 3 An outline of the iRIC Software, its functions and features. ........................11
Fig: 3. 1 Channel with series of impermeable groin ...................................................18
Fig: 3. 2 Channel with series of impermeable groin (with grid) on iRIC Nays2DH .18
Fig: 3. 3 Channel with series of permeable groin........................................................19
Fig: 3. 4 Channel with series of permeable groin (with grid) on iRIC Nays2DH.......19
Fig: 3. 5 Channel with series of combined groin.........................................................20
Fig: 3. 6 Channel with series of combined groin on iRIC Nays2DH..........................20
Fig: 4. 1 Channel and grids with groin (90° orientation). ...........................................23
Fig: 4. 2 Comparison of resultant velocity profile with the available previous study
for 90° groin..................................................................................................24
Fig: 4. 3 Simulated velocity vectors around the groins for (a) series of impermeable,
(b) series of permeable groin, and (c) series of combined groins.................25
Fig. 4.4 Simulated streamlines around the groins for (a) series of impermeable, (b)
series of permeable, and (c) series of combined groin..................................27
Fig: 4. 5 Velocity magnitude around the groins for (a) series of impermeable (b)
series of permeable and (c) series of combined groin...................................28
Fig: 4. 6 Simulated velocity fields in the 1st
groin field..............................................29
Fig: 4. 7 Comparison of simulated velocity profiles along the channel at D/S of 1st
groin..............................................................................................................30
Fig: 4. 8 Simulated velocity fields at the mid portion of 3rd
and 4th
groin. .................30
Fig: 4. 9 Comparison of simulated velocity profiles at the mid portion between 3rd
and
4th
groin.........................................................................................................31
8. vii
Contents
ABSTRACT....................................................................................................................i
ACKNOWLEDAGEMENT ........................................................................................ iii
NOTATIONS................................................................................................................iv
LIST OF FIGURES .......................................................................................................v
LIST OF TABLES........................................................................................................vi
CHAPTER I INTRODUCTION..............................................................................1
1.1 General ........................................................................... 1
1.2 Background ..................................................................... 1
CHAPTER II LITERATURE REVIEW ...................................................................3
2.1 General............................................................................ 3
2.2 Literature review.............................................................. 3
2.3 Generalized simulation procedure ..................................... 6
2.3.1 Simulation and modeling .................................................. 6
2.3.2 Components of a numerical solution ................................. 6
2.3.3 Discretization approaches ................................................. 6
2.3.4 Numerical grid ................................................................. 7
2.3.5 Properties of numerical solution methods .......................... 7
2.4 iRIC software .................................................................. 8
2.4.1 Features of the flow field calculation model..................... 11
CHAPTER III METHODOLOGY ............................................................................13
3.1 Introduction ................................................................... 13
3.2 Software used ................................................................ 13
3.3 Basic equation ............................................................... 13
3.3.1 K-ε model ..................................................................... 13
3.3.2 Equation of continuity ................................................... 14
3.3.3 Equation of motion ........................................................ 14
3.3.4 Bottom friction calculation method ................................ 16
3.4 Operational procedure of software .................................. 16
3.5 Calculation conditions.................................................... 20
3.6 Working procedure......................................................... 20
CHAPTER IV SIMULATION OF FLOW................................................................22
4.1 General.......................................................................... 22
4.2 Verification of numerical model ..................................... 22
9. viii
4.3 Simulated flow fields ...................................................... 24
4.4 Simulated streamlines ..................................................... 25
4.5 Comparison of simulated velocity profiles ....................... 27
CHAPTER V CONCLUSION AND RECOMMENDATION ................................33
5.1 Introduction ................................................................... 33
5.2 Conclusion..................................................................... 33
5.3 Recommendations for further study................................. 33
REFERENCES ............................................................................................................35
10. 1
CHAPTER I
INTRODUCTION
1.1 General
Bangladesh is a great delta formed by the three mighty river systems: the Ganges, the
Brahmaputra and the Meghna. There are around 400 rivers in the country. Most of the
basin area of major rivers of the country is located outside the country, serving as
the predominant sources for rivers that go with flow through the nations China, Bhutan,
Nepal and India, and eventually passing into the Bay of Bengal to the south of
Bangladesh. Every year hundreds of hectares of land are eroded by means of the rivers
(NWMP, 2001). No other disasters are as disastrous as riverbank erosion
in phrases of long-term effect on people and society (Elahi, 1991). To shield river
erosion, use of groins is very popular and effective. The following sections describe
background, objectives and scope of the present study.
1.2 Background
Recurrent flood phenomena occurred after heavy rainfall, riverbed and bank of the
rivers tend to erode due to high velocity. Also, there are some other reasons for bank
erosion like very mild slope in riverbed and water surface, loose sedimentary formation
in channel boundaries, small depth of flow due to siltation of huge sediment load
coming from upstream, and so on. The simulation of water flow in rivers has been the
subject of many researches in the field of hydraulics and river engineering (Azevedo
and Gates, 2000). In river and coastal engineering, groins are very important structures
for river navigation, coastal protection, and beach reclamation (Sarveram and Shamsai,
2012). These hydraulic structures have been constructed in river bank in order to deflect
the flowing water away from vulnerable zone. The main purpose of building up of such
obstacles on natural river bank is to divert the direction of water flow so that bank
erosion can be eliminated. Construction of such obstacles against water flow causes
significant change in flow patterns, sediment transport and bed topography. Many
experimental and numerical researches have been done in order to examine flow pattern
and scouring around groins (Francis et al., 1968), (Rajaratnam and Nwachukwu, 1983),
(Choudhury et al, 1995), (Tang and Ding, 2007), (Hossain et al., 2012), (Pandy et al.,
11. 2
2015), (M. Shahjahan et al, 2018). In different conditions of groin length, groin
installation angle towards the approaching flow, permeable or impermeable states,
submerged and non-submerged states and number of groins, and so on (Yeo et al.,
2005). Due to the variety in the configuration of groins, flow separation and
recirculating length would be greatly different, which is a challenge to the applications
of numerical models (Quanhong and Pengzhi, 2007).
In stabilizing river channels, groins are extensively used. Impermeable groin imposes a
huge obstruction to flow, and change the flow profile abruptly. Fully permeable groin
cannot modify the flow environment rightly, and flow near bank occurs, which could
affect the bank when associated with oblique flow. Combined groins, which have
impermeable parts near bank, could improve the flow field to have favorable
environment for groin and bank stability.
In this study, open channel flow with three different arrangements of groins in series –
impermeable, permeable and combined groins, is simulated with a two-dimensional
(2D) numerical model, iRIC Nays2DH.
1.3 Objectives
The main objective of the present study is to investigate flow profiles around different
types of groins. So that, the effects of groins in an open channel can be evaluated. The
specific objectives are as follows:
To simulate the flow through open channel with groins placed in a series.
To determine the flow fields and compare the channel responses due to three
different groin structures.
1.4 Scope of the study
In nature, there are various flow conditions, complex channel geometry and boundary
materials. The channel boundaries are composed of loose sedimentary materials, very
irregularity in the geometry of channel boundary, flow varies highly there. However, a
simplified open channel has been considered in the present study. A straight channel
with immoveable boundary is considered and constant flow is maintained in the study
to investigate the effects of groin structures.
12. 3
CHAPTER II
LITERATURE REVIEW
2.1 General
Groin is an elongated obstruction having one end on the bank of the stream and the
other end projecting into the current. It reduces the flow velocity in the critical area and
encourage deposition of sediment in the downstream area of the structures near the bank
line. The simulation of flow in rivers has been the subject of many researchers in the
field of hydraulics and river engineering. In this chapter, the available previous studies
made on channels with groins are reported. Besides, some basic information on groin
functioning, concepts of numerical modeling and description of iRIC Nays2DH
software are illustrated.
2.2 Literature review
Groins have been used extensively all over the world as river training and bank
protection structure to reduce the current along the stream bank, thus reducing the
erosive capacity of the stream and in some cases including sedimentation between
groins. In the groin-flow study, the dead-water zone between groins is called the groin
field. Secondary flow produces and develops in the groin field, and one or more vortices
dominate the flow structures in the zone. A mixing layer is prevailed at the interface
between the groin field and the main channel. Eddies are produced near the groins and
then move downstream owing to the disturbance of the flow by the groins. The mean
velocity in the main channel exceeds that of the groin field. The properties of groin flow
significantly influence the velocity profile, transport of sediment and pollutants in
rivers. Groin flow properties, including the velocity distribution, turbulent kinetic
energy and flow structures, are related to groin parameters, such as the groin height,
groin length, angle to the bank, and aspect ratio (the ratio of the groin length to the
distance between two adjacent groins).
In broad aspect, the functions of groins not only to keep banks from erosion
(Przedwojski 1995), they improve the navigation capability of the main channel,
13. 4
restores river ecosystems (Hood, 2004), and increases biological diversity. Groins can
protect neighboring banks from scouring by guiding flow to a certain direction. The
flow is concentrated in the center of the river, and the velocity simultaneously increases
in the main channel and the vicinity of groin heads (Wu et al., 2005). In contrast, the
groins can induce a rising of water level during extreme conditions and hence, increase
the risk of levee overtopping and collapsing (Pinter et al. 2001).
The first research carried out in this field by Francis et al. (1968). They considered
separation zone for various types of groin in a rectangular flume, but they did not
measure the flow velocities. Researches done by Rajaratnam and Nwachukwu (1983)
did velocity measurements in the flow induced by groins. Also, Choudhury et al. (1995)
applied numerical methods for the solution of flow field around groins. Molls et al.
(1995) also developed a general mathematic model to solve the unsteady two-
dimensional depth averaged equations by combining it with a constant eddy viscosity
turbulent model. Various models in considering turbulence under different flow
conditions of and groin dimensions are utilized to investigate scour around groins by
Zhanfeng and Xiaofeng (2006), Quanhong and Pengzhi (2007), Tang and Ding (2007),
and so on.
Kim and Choi (2003) conducted an experiment on numerical simulations of open-
channel flows in a bend using the finite element method. They used the 2D numerical
algorithm for this simulation. The proposed model was applied to 180° bend
experimented by Rozovskii (1961). The simulated results compare favorably to
measured data. Then, the model was used to simulate flows in a 7.7 km curved reach in
the Han River, Seoul, Korea. They also investigate the impact of planting vegetation on
each side of floodplain.
Masjedi and Foroushani (2012) studied the effect of different shape of single spur dike
in river bend on local scour. Hossain et al. (2012) applied a numerical model on a
rectangular straight channel which is 13.3m long and 0.8m wide. The barb structure is
installed as a obstacle at 45°, 90° and 135° on the upstream portion of river channel.
The length of the barb is 24cm, one third of the cross-section. The numerical
simulations have been done considering sediment transport. Barbs have been used by
14. 5
Natural Resources Conservation Service (NRCS) of US department of agriculture, in
Origon for river and stream bank protection since the late 1980.
Permeable spur dikes have the advantages of being more stability requiring easier
maintenance than impermeable ones (Kang et al, 2011). Scour around spur dikes occurs
under both clear water and live bed conditions. Where there is no transport of sediment
by the approaching flow to the region of scour activities around the spur dike or under
live bed scour where sediment is transported by the approaching flow as bed load or
suspended load to the scour hole at the spur dike (Pandy et al., 2015). M.Shahjahan et
al, (2018) predicted velocity profiles and bed shear stress profiles for 45º, 90º and 135º
angles of groin in a straight channel.
Most of the studies through experiments or numerical simulations were done about a
single groin with different orientation, and they found out several merits and demerits
of impermeable and permeable groins. For impermeable groins, flow is obstructed
largely, and because of flow separation and strong vortices developed near the groin
head, huge scour occurs near groin, which hampers stability of groins. In case of
permeable groins, the flow partly penetrates the structures which results in a
considerable reduction in velocity, vortex strength and shear force at the nose of the
spur dike (Li et al. 2005). Fully permeable groins allow flow near bank, and do not
divert the flow far from the bank. However, from the experimental investigation, this
has been found that a combined groin (a combination of impermeable and permeable
part) can influence and develop dead zone in the groin field (Alauddin et al., 2011).
In the present study, numerical simulations have been conducted for investigating flow
fields around groins of three different designs. These groin models are – impermeable,
permeable and combined. The comparison of change in velocity profiles due to
different groin models can give important information to explore a suitable design of a
groin.
15. 6
2.3 Generalized simulation procedure
2.3.1 Simulation and modeling
Simulation of a system is used for understanding the physics of the process of the
system in time and space. Generally the simulation process contains following steps:
Conceptualization of process of physical system.
Transforming the process of physical system by into partial differential
equation.
Transforming the partial differential equation into algebraic equations or
numerical equations.
Development of the solution algorithm of the numerical equations.
The computed codes are written.
Finally, the model is validated.
2.3.2 Components of a numerical solution
A numerical solution method contains following components –
Mathematical Model,
Discretization Approach,
Coordinate and Basis Vector Systems,
Numerical Grid,
Finite Approximations,
Solution Method,
Convergence Criteria,
Discretization Approach and Numerical Grid are two most important components.
Here, these have explained.
2.3.3 Discretization approaches
There are three discretization approaches –
Finite Difference Method
Finite Volume Method
Finite Element Method
16. 7
2.3.4 Numerical grid
The discrete locations at which the variables are to be calculated are defined by
numerical grid which is essentially a discrete representation of the geometric domain.
It divides the solution domain into a finite number of sub domains (grids, elements,
control volumes, etc).
Continuous function is replaced by discrete function as grid or elements in a
process, which is called discretization. Finite difference grid is shown below
(Fig. 2.1).
Discrete time steps approximate continuous time.
Fig. 2. 1 Finite difference grid
2.3.5 Properties of numerical solution methods
The solution method should have certain properties. In most cases it is not possible to
analyze the solution method. One analyzes the components of the method; if the
components do not possess the desired properties, neither will the complete method but
the reverse is not necessarily true. Some important properties are given below –
Consistency
Stability
Convergence
Conservation
Roundedness
Realize ability
Accuracy
17. 8
Fig. 2. 2 Conceptual relationship between consistency, stability and convergence.
2.4 iRIC software
The International River Interface Cooperative (iRIC) is an informal organization made
up of academic faculties and government scientists with the goal of developing,
distributing, and providing education for a public-domain software interface for river
modeling. Nays2D is an analytical solver for calculation of unsteady 2D plane flow and
riverbed deformation using boundary-fitted coordinates within general curvilinear
coordinates. Professor Yasuyuki Shimizu of Hokkaido University firstly developed the
solver’s prototype in the 1990s. After many improvements, first it was adopted in 2004
as a calculation solver for incorporation in the iRIC-Nays riverbed deformation
calculation pre post software of the Foundation of Hokkaido River Disaster Prevention
Research Center (Version 1.0).
Later refined by the inclusion of dynamic memory allocation by Ichiro Kimura of
Hokkaido University and outfitted with a bank erosion model by Yasuyuki Shimizu
and a HotStart function by Toshiki Iwasaki of Hokkaido University, Nays2DH (Version
2.0) was distributed as one of the solvers included with iRIC in 2010 at the release of
iRIC Version 1.0.
18. 9
Further functional additions included the incorporation of a mixed-diameter multilayer
model proposed by Toshiki Iwasaki. A river confluence model proposed by Takuya
Inoue and Michihiro Hamaki of Kaihatsu Koei Co. Ltd. Nays2DH was registered as a
calculation solver for iRIC Version 2.0 in March 2011 under the planning and
supervision of Kazutake Asahi from the Foundation of Hokkaido River Disaster
Prevention Research Center (Version 3.0).
This model has an established reputation for calculation of unsteady flows accompanied
with turbulence and laminar flow and it is capable of dynamically showing the realistic
motions of unsteady eddies. In addition, its riverbed deformation calculations can
reproduce the generation, development and migration of sandbars with high precision.
There have been many examples of Nays2D being used on actual rivers for purposes
such as assessing the effects of trees and vegetation, making flood calculations,
studying the effects of inflowing rivers and simulating bank erosion disasters. Nays is
a model developed at Hokkaido University; the details of the model are described in
Shimizu (2002). The title of the model is not an acronym; it is an Ainu word meaning
“small river”.
There are four primary features of Nays:
It is two-dimensional (vertically integrated).
It is fully unsteady.
It is cast in a general, non-orthogonal coordinate system with variable cell size.
It includes a much more sophisticated method for treating turbulence that
includes both a horizontal large eddy simulation and a suite of turbulence
closures.
The non-orthogonal coordinate system allows more precise fitting of the coordinate
system to suit arbitrary channel curvature and variable width. More importantly, the
more detailed treatment of turbulence and large eddies allows predictions of time-
variable behavior even for steady discharges. Nays is currently the most sophisticated
model within iRIC in terms of handling advection of momentum and strong local
unsteadiness. Nays also includes full sediment-transport capabilities and morphologic
change prediction, so the impacts of unsteadiness on bed change can assessed with this
approach. Furthermore, Nays provides a variety of particle-tracking information.
19. 10
Formed in late 2007, the group released the first version of this interface, iRIC, in 2009.
The purposes of the activities of this project are creation of opportunities for interaction
and provision and exchange of information on issues to utilize knowledge and
engineering about rivers. To support creation of more beneficial and sustainable river
environments among administrative engineers, construction consultant companies,
river researchers and students focusing on development of software for analysis of
stream flows, river bed fluctuations and floods. The iRIC software interface includes
models for two- and three-dimensional flow, sediment transport, bed evolution,
groundwater-surface-water interaction, topographic data processing, and habitat
assessment, as well as comprehensive data and model output visualization, mapping,
and editing tools. All of the tools within iRIC are specifically designed for use in river
reaches and utilize common river data sets. The models are embedded within a single
graphical user interface so that many different models can be made available to users
without requiring them to learn new pre- and post-processing tools. iRIC provides a
comprehensive, unified environment in which data that are necessary for river analysis
solvers (hereafter, solvers) can be compiled, rivers can be simulated and analytical
results can be visualized. The highly flexible iRIC interface allows various solvers to
be imported. Upon selecting the solver, iRIC selects functions suitable for the solver
and prepares the optimal simulation environment. Because the iRIC functions vary
depending on the solver, the method of using the iRIC application depends on the
solver.
The iRIC software consists of three functions: preprocessor, postprocessor, and solver
(Figure 2.3)
20. 11
Fig. 2. 3 An outline of the iRIC Software, its functions and features.
2.4.1. Features of the flow field calculation model
As a coordinate system, the general curvilinear coordinate system is adopted, allowing
direct consideration of complex boundaries and riverbed shapes.
Calculations involving the confluence of a main channel and a tributary can be
performed.
For the finite-difference method applied to the advection terms in equations of
motion, the user can choose the upwind difference method (primary precision)
or the CIP method. This is a high-order finite-difference method. By using a
cubic polynomial as an interpolation function, numeric diffusion is reduced,
thus enabling high-precision local interpolation.
For the turbulent field calculation method, the user can select one from Constant
eddy viscosity model, Zero-equation model, and K-ε model.
Various settings are possible for boundary conditions of the upstream and
downstream ends, including periodic boundary conditions, downstream end
21. 12
water surface elevation setting and upstream end velocity setting. This makes it
easy to set boundary conditions from limited observation data.
For setting the initial water surface profile, the user can select from among
[Constant slope], [Line], [Uniform flow calculation] and [Non-uniform flow
calculation].
The bottom friction evaluation method is set by using Manning's roughness
parameter. This parameter can be set to each computational cell.
Any obstacle within the calculation target area can be taken into account on a
calculation-cell basis. For each calculation cell, a flag can be set to define an
obstacle. By this means, river structures such as bridge piers can be easily
incorporated in calculation.
The effect of vegetation for the flow calculation can be introduced as a drag
force. The user can set the density of vegetation in each computational domain.
22. 13
CHAPTER III
METHODOLOGY
3.1 Introduction
In the present study, three different types of series groin models were considered for
investigating the flow pattern due to a constant flow. In this chapter, the details of flow
domain, flow parameters, and simulation of flow due to different groin series are
presented. The simulation works were conducted using iRIC Nays2DH. A brief
description of 2D numerical model, iRIC Nays2DH and its operational procedure have
been given in the following sections.
3.2 Software used
In this study, iRIC Nays2DH is used to simulate the flow fields in an open channel with
groins. iRIC (International River Interface Cooperative) is a pre- and post-processing
software application and framework for computation of flow and sediment transports
in rivers. The application through a Graphical User Interface (GUI) allows the model
user to build, run, and visualize the results from the system. The GUI provides tools for
building both structured and unstructured grids, defining topography and other
boundary conditions on the grid, and defining grid-dependent values such as grain size,
vegetation, and obstacles by mapping measured values to the grid or by creating user-
defined polygons with attributes of grid dependent value. It combines the functionality
of MD_SWMS, developed by the USGS (U.S. Geological Survey) and iRIC-Nays,
developed by the Foundation of Hokkaido River Disaster Prevention Research Center.
3.3 Basic equation
3.3.1 K-ε model
The eddy viscosity coefficient in the standard k-ε model can be expressed by the
following equation:
where, Cμ is a model constant. k and ϵ are obtained by the following equations:
23. 14
Table: 3. 1 Model Constants
Where C1ε, C2ε, σk and σε are model constants whose respective values are shown in
Table 2.1 note that Pkv and Pεv are calculated with the following equations:
3.3.2 Equation of continuity
The equation of continuity is given below:
3.3.3 Equation of motion
The equation of motion is given as:
Where,
Cμ C1ε C2ε σk σε
0.09 1.44 1.92 1.0 1.3
24. 15
As for diffusion terms Dξ and Dη in the motion equation in general coordinates, since
developing those terms will make the number of terms huge, they are simplified by
assuming the following conditions:
The second-order derivative for the metric coefficient is assumed to be locally zero.
Those terms are locally treated as pseudo-orthogonal coordinates. As a result, the
diffusion terms can be approximated as follows:
Where, ξr and ηr are parameters each representing the ratio of the local grid size in
general coordinates to the full-scale length of the grid. They are defined as follows:
Note that to derive the approximate equations of Dξ and Dη above; the following
relations are used, based on the assumption of a relationship of local orthogonally.
25. 16
Where, θ represents the angle formed by the x axis and the ξ axis (or the y axis and the
η axis).
3.3.4 Bottom friction calculation method
In Nays2DH, bottom friction is set using Manning's roughness parameter. For
Manning's roughness parameter, the user can define this parameter in each
computational cell.
Riverbed shearing forces τx and τy are expressed by using coefficient of riverbed
shearing force Cf. The coefficient of riverbed shearing force Cf is estimated by
Manning's roughness parameter nm as follows:
This Manning’s roughness parameter can be estimated from the relative roughness
height, ks, by using the Manning – Strickler equation as follows:
3.4 Operational procedure of software
The following are the basic procedures for operating Nays2DH with iRIC:
1. Launching Nays2DH
Prepare to use Nays2DH with iRIC
2. Create new project
Create a new project select Nays2DH iRIC.3x 1.0 64bit
3. Creating Calculation grids
Create a grid for calculation import channel measured data. Which
prepare in excel at .riv format.
26. 17
Three different types of groins in series were considered in the present study. These
models are – Impermeable, permeable and combined (combination of impermeable and
permeable parts) groins. All groins are placed perpendicular to the channel bank. A
nonlinear 𝑘-𝜀 model is used to predict the turbulent flow field by capturing the
anisotropic turbulence. Cubic interpolation pseudo-particle (CIP) method was used for
advection term. The basic equations are discretized as fully explicit forms and solved
successively with the time increment in step by step. It is solved using iterative
procedure at each time step.
The concrete channel under hydraulic engineering laboratory of DUET, Gazipur, which
has the dimension of length 20.50 m, width 1.52 m and depth 1.12 m is considered in
the numerical simulation. The information of channel and groin models have been
presented in Tables 3.2 - 3.5.
Table: 3. 2 Channel dimension
Length of the channel 20.50 m
Width of the channel 1.52 m
Depth of the channel 1.12 m
5. Making simulations
Use Nays2DH to run the simulation
6. Visualizing the calculation results
Visualize the simulation results, such as flow velocity, water depth,
by using vector map to see whether the simulation has successfully
run and save the file.
4. Setting calculation conditions
Set simulation discharge, boundary conditions, roughness and other
items
27. 18
Table: 3. 3 Groin Parameter (Impermeable)
Fig. 3.1 shows model setup and Fig. 3.2 shows calculation grid for impermeable groin.
Fig: 3. 1 Channel with series of impermeable groin
Fig: 3. 2 Channel with series of impermeable groin (with grid) on iRIC Nays2DH
Table: 3. 4 Groin parameter (Permeable)
Length of the each groin 0.45m
Size of block(each) 3cm
Size of opening(each) 6cm
Thickness of the groin 5cm
Total impermeable portion 15cm
Total permeable portion 30cm
Number of groin 5 Nos
Length of the groin 0.45m
Thickness of the groin 5cm
Number of groin 5 Nos
Position of first groin 7.5 m from U/S section
c/c distance between groin 0.90m
28. 19
Fig. 3.3 shows model setup and Fig. 3.4 shows calculation grid for impermeable
groin.
Fig: 3. 3 Channel with series of permeable groin
Fig: 3. 4 Channel with series of permeable groin (with grid) on iRIC Nays2DH
Position of first groin 7.5 m from U/S section
c/c distance between groin 0.90m
Table: 3. 5 Groin parameter (Combined)
Fig. 3.5 shows model setup and Fig. 3.6 shows calculation grid for impermeable groin.
Length of the each groin 0.75m
Total impermeable portion 0.45m
First impermeable portion 0.30m
Size of block (each) 3cm
Size of opening (each) 6cm
Thickness of the groin 5cm
Number of groin 5 Nos
Position of first groin 7.5 m from U/S section
c/c distance between groin 0.90m
29. 20
Fig: 3. 5 Channel with series of combined groin
Fig: 3. 6 Channel with series of combined groin on iRIC Nays2DH
3.5 Calculation conditions
A certain flow condition was considered in this study, and it was maintained same for
all cases. This condition has been explained below:
A constant discharge of 0.05 m3
/sec is used in the simulation. The depth of flow in the
channel was kept constant, and it was around 22.5 cm in the channel. The flow
discharge remains same for all the cases in this study. Related parameters are given in
Table 3.6 below:
Table: 3. 6 Flow conditions
Discharge (m3
/sec) 0.05
Depth of flow (m) 0.225
Time period (minutes) 30
Bed slope (𝑆𝑜) 0.001
3.6 Working procedure
30. 21
The numerical simulation works were done as mentioned in the following procedure:
i. First, the channel geographic data have been collected and prepared for making
calculation grid.
ii. Then, the geographic data is imported, and grid is created.
iii. In the grid made in the previous step, obstacle cells are defined in some certain
locations to function these as groins as per groin parameters mentioned earlier.
iv. After that, calculation condition is given for computation. Constant discharge at
upstream and constant depth with zero velocity gradients was given as
downstream boundary conditions.
v. The simulations are done and the calculation results are extracted for further
analyses.
31. 22
CHAPTER IV
SIMULATION OF FLOW
4.1 General
2D numerical model Nays2DH is used to simulate the flow field in a straight open
channel with 90º groin angled with the flow direction with three different series of groin
models. The simulation has been performed utilizing channel and flow conditions and
analyzed for comparing velocity profiles induced by different groins. These have been
explained in the following sections.
4.2 Verification of numerical model
The model is verified with experimental data of Rajaratnam and Nwachukwu (1983),
where they investigated the flow-fields in a laboratory flume near a groin-like structure.
The flow-fields of the physical model are well reproduced by the numerical model
outside of the groin field, but some discrepancies are present downstream of the groin
where the flow is highly skewed.
The sketch of the flow domain for flows in an open channel with groin of 90° angled
to the direction of flow which was performed under the same conditions of the
experiments conducted by Rajaratnam and Nwachukwu (1983). The length of the
channel 6m, width of the channel 0.9m, discharge 0.0430 𝑚3
/𝑠, water depth at
downstream 0.001m, manning’s roughness co-efficient 0.01 were taken .
32. 23
Fig: 4. 1 Channel and grids with groin (90° orientation).
For 90° groins, the resultant velocity profile is compared with available experimental
result measured at y/l =2 and 3, where l = 141mm is the length of the groin. Fig. 4.2
shows the comparison of velocity profile for lateral distance (y/l =3 ). Here the initial
flow velocity profiles for different lateral distance (y/l). Here the initial flow velocity
and water depth were 𝑈0 = 0.50 m/s and H = 0.189m, respectively. In the figure,
velocity is normalized by 𝑈0. In the figure, x/l = 0 indicated the groin position along
flume direction.
Good agreements are found between experimental and calculated results. For the
velocity profile, the result obtained by iRIC Nays2Dh is very near to the experimental
result. The calculated results under predict the experimental data in the downstream
zone of the groin. The numerical result provide by (Quanhong and pengzhi, 2007) and
(Sarveram et al., 2012) also under predicted the experimental data largely in this region.
This may be due to the very high velocity gradient arising in this region which makes
the depth-averaged model inapplicable. Otherwise, the possible reason may come from
the experimental measurement errors in this region. In the figure only present data
compared with the experimental data by Rajaratnam and Nwachukwu (1983).
(a) Velocity along y/l= 2
0
0.5
1
1.5
2
-6 -4 -2 0 2 4 6
w/u
x/l
Calculated (present study)
Measured (Rajaratnam & Nwachukwu, 1983)
33. 24
(b) Velocity along y/l= 3
4.3 Simulated flow fields
Fig. 4.3 shows the simulated velocity vectors of the flow field around the groin for three
different series of groin with a constant flow. The upstream flow of channel started
from right side. For all the cases, the model is found to reproduce the general flow
features of the flow field around the groin successfully. From the simulated results, it
is seen that at the upstream boundary the flow is uniform and hence the flow vectors
are straight and parallel to bank. However, when the flow approaches the groin, the
flow is deviated towards the right bank compared to the left due to obstruction of flow
by the groin. Recirculation of flow zone is observed just downstream region of the first
groin for impermeable series of groins. In permeable condition, the velocity vectors are
not disturbed as found in the impermeable case, though these have same length. For the
impermeable series portion, the velocity vectors are too closed at the main channel area
after the first groin. In combined series of groin, the velocity vectors are modified
compared to both impermeable and permeable cases. Small recirculation of flow occurs
at the downstream of each groin along the length.
0
0.5
1
1.5
2
-6 -4 -2 0 2 4 6
w/u
x/l
Calculated (present study)
Measured (Rajaratnam & Nwachukwu, 1983)
Fig: 4. 2 Comparison of resultant velocity profile with the available previous study for 90°
groin
34. 25
(a)
(b)
(c)
Fig: 4. 3 Simulated velocity vectors around the groins for (a) series of impermeable,
(b) series of permeable groin, and (c) series of combined groins.
4.4 Simulated streamlines
Fig. 4.4 shows the streamline around series of groin for all cases such as
impermeable, permeable and combined series condition, which is obtained by
the present study. From the streamline contour it is found that at the position of
groin head the flow is deviated towards the opposite bank and at the downstream
of the groin. In permeable series of groins the flow pass through the permeable
U/S
U/S
U/S
35. 26
portion. The flow stream line is less disturb as impermeable groins. Due to the
permeable portion on the combined series of groin the flow can occur along the
permeable portion so that the velocity intensity reduced on the upper portion of
the groins. The Figures 4.2 depict that series of impermeable groin deviations of
streamline are higher compared to series of combined groin. In the combined
series of groin shows the least deviation compared to series of impermeable
groin.
(a)
(b)
U/S
U/S
36. 27
(c)
Fig. 4.4 Simulated streamlines around the groins for (a) series of impermeable, (b)
series of permeable, and (c) series of combined groin.
4.5 Comparison of simulated velocity profiles
Fig. 4.5 shows the predicted velocity magnitude of the flow field around the groin for
three different series of groin with a constant flow. The results are found to be similar
in nature. For all cases, the velocity contour along the left bank is higher than right bank
at the downstream region of the groin; it indicates the deflection of flow towards right
bank and sheltering of flow by groin at left bank. For the impermeable series of groin
the velocity of flow is very high at just upper position of groins head. The velocity of
flow is pick at the first, fourth and fifth groin head. Though the same length between
impermeable and permeable groin the velocity is very low for permeable groins. It is
due to in the permeable series of groin the total impermeable length is 15cm, where the
impermeable groins total impermeable length is 45cm. At the same time for the
combined series of groin the velocity is pick after the groins head but the intensity of
flow velocity is comparatively low than impermeable series of groin. For the combined
series of groin the velocity intensity at the impermeable zone is very low and in the
permeable zone flow intensity increase very slowly. Though large dead zone occurs at
the downstream of series impermeable groin but here also produced one or more
recirculation with high velocity. Scouring have done in this area. So the stability of
groins structure is affected by scouring. In the series combined groin the velocity
intensity very large at the 5th
groin head. In the interior of the series combined groin,
the dead zone occurs that is comparatively large and the recirculating area is small with
low velocity with respect to impermeable series of groin.
U/S
37. 28
(a)
(b)
(c)
Fig: 4. 5 Velocity magnitude around the groins for (a) series of impermeable (b)
series of permeable and (c) series of combined groin.
The figure given below (Fig. 4.6) shows the predicted velocity profiles for series of
impermeable, permeable and series of combined groin at different points along the
channel. For each circumstance, the longitudinal velocity profiles are compared at a
lateral position of the channel bed. In the graph, horizontal axis presents the velocity
magnitudes of the flow and the vertical axis represent the lateral distance of the channel
bed.
38. 29
Fig: 4. 6 Simulated velocity fields in the 1st
groin field.
Figure 4.6 represent the position of 1st
groin D/S and 2nd
groin U/S portion in different
series groin case. Figure 4.7 represents the flow velocity at the downstream of the 1st
groin along the channel width. Both figure shows the comparison the velocity intensity
in these area produced by the series of impermeable, permeable and series of combined
groin. The velocity intensity produced by the impermeable groin at the D/S along the
groin length is very low intensity. The velocity intensity reached at pick position just
upper the position of the groin head. For permeable series of groin condition the
velocity along the groin length is high with respect to impermeable series of groins. The
velocity intensity through the width of channel is medium due to the resistant portion
is very small comparatively impermeable groins. At the same time for the combined
groin, the velocity intensity in the impermeable zone is lower than the impermeable
groin. After the impermeable zone the velocity intensity rise a small portion and varies
depending upon the permeable and impermeable portion along the length of the groin.
At the groin head the velocity increase slightly but the intensity is low rather than
impermeable groin head. In this point a dead zone produced by impermeable and
combined groin but for permeable groin no dead zone produced. Single but large
recirculation produced by impermeable groin, for permeable groin no recirculation
produced and for combined groin single recirculation produced a low flow intensity.
39. 30
Fig: 4. 7 Comparison of simulated velocity profiles along the channel at D/S of 1st
groin.
Fig: 4. 8 Simulated velocity fields at the mid portion of 3rd
and 4th
groin.
Fig. 4.8 represents the mid groin field, i.e area bounded by 3rd
and 4th
groin for all groin
cases. Fig. 4.9 represents the flow velocity at the middle of the 3rd
and 4th
groin along
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8
Velocity
(m/s)
Transverse Distance (m)
Impermeable Permeable Combined
40. 31
the channel width. The graph shows the evaluation of velocity intensity in middle
position along the width produced by the series of impermeable, permeable and series
of combined groins. Here the flow velocity intensity for the impermeable groin is very
low along the length of groin and after the groin head the velocity is instantly higher.
For the permeable groins the velocity have a small change with respect to impermeable
groins. At the same time the velocity intensity for the combined groin is comparatively
low in the impermeable zone. In the permeable zone the velocity intensity is increase
but lower than velocity intensity produced by impermeable groin. The pick flow occur
after a certain distance from the head of combined groins. This makes the combined
groin more stable in sustainable life. In impermeable groin condition approximate two
large recirculation produced and for combined groin two small recirculation produced.
Due to the high velocity no deposition occurs in that area and maintain the flow depth.
Though the total impermeable portion between impermeable and combined groins are
same but the velocity reduction pattern is very good for combined groins and the dead
zone produced by combined groins is large. The size of recirculation area also small.
Fig: 4. 9 Comparison of simulated velocity profiles at the mid portion between 3rd
and
4th
groin.
From the simulation data, this can be found that installation of permeable groin
produces slow flow near side or bank. Although, a dead zone is created in the groin
0
0.1
0.2
0.3
0.4
0.5
0.6
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8
Velocity
(m/s)
Transverse Distance (m)
Impermeable Permeable Combined
41. 32
field due to impermeable groin, strong recirculation of flow might be present which can
attack the bank line. The flow velocity near the head of the impermeable groin is found
very high. So that the possibility of scouring near groin is very high, and thus stability
of the groin might be hampered. As the length of permeable groin was kept same of
impermeable one, velocity at main channel area is not increased enough, which could
assist improving navigation facility. In permeable groin condition though the velocity
reduced but no dead zone produced at the groin bank side. In the combined series of
groins, the total impermeable portion is same as impermeable groin. Even though, this
has same obstruction, because of the presence of permeable part with impermeable part,
velocity of flow is not increased much near the head of groin; so that, less scour might
be expected. In addition, due to the impermeable portion near bank, a dead zone of less
circulation of flow is created which might influence deposition of sediment near bank.
42. 33
CHAPTER V
CONCLUSION AND RECOMMENDATION
5.1 Introduction
Two-dimensional numerical model Nays2DH was employed in the present study to
investigate the characteristics of flow field developed around groin structures. From the
numerical simulation performed in the study, the velocity profiles are compared for
different types of series groin for evaluating their performance. The following sections
describe conclusion and recommendations.
5.2 Conclusion
This study has given the detailed information regarding the flow fields due to groins in
an open channel. From the numerical simulation, the general flow features around a
groin is reproduced successfully. The flow fields found in the study can be described
as:
i. The flow at upstream side is uniform.
ii. Circulation of flow is found at the downstream of the groin that is created
due to sheltering the flow by impermeable groin.
iii. High velocity zone is created after the groin due to the deflected flow.
From the comparison of flow profiles due to series of impermeable, permeable and
combined groins, this is observed that the velocity is maximum near the head of
impermeable groin, and this is much less for permeable and combined groins. Strong
circulation of flow is present for impermeable groin; however, a dead zone of less
circulation is created near side of channel due to combined groin.
5.3 Recommendations for further study
Following recommendation can be made for further research:
i. The study can be extended to simulate the sediment transport, nutrient transport
and bed deformation due to groins.
ii. As the flow near a groin is distinctly three-dimensional, it is recommended to use,
a 3D numerical model needs to study flow vortex and local scour.
43. 34
iii. The model can be applied for different spacing between two groins to study the
effect of spacing.
iv. The study can be extended for different groin length to channel width ratios to
study the effect of groin length to the flow field and sediment transport.
44. 35
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