Project report12

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TURBULENCE STUDY OF 2D - MAGNETOHYDRODYNAMIC
FLOW OVER SQUARE RIB IN A OPEN CHANNEL
A THESIS SUBMITTED IN PARTIAL FULFILMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
Master of Technology
In
Mechanical Engineering
By
SUJAY KUMAR PATAR
HALDIA INSTITUTE OF TECHNOLOGY ,HALDIA pin-721657 w.b (india)
2018(may)

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TURBULENCE STUDY OF 2D - MAGNETOHYDRODYNAMIC
FLOW OVER SQUARE RIB IN A OPEN CHANNEL IN COMERCIAL
ANSYS CODE SOFTWARE ENVIROMENTRESULT ANALYSIS
THESIS SUBMITTED IN PARTIAL FULFILMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
Master of Technology
In
Mechanical Engineering
UNDER THE GUIDANCE OF
Mr. Manas kumar Bhukta
Assistant professor,
HALDIA INSTITUTE OF TECHNOLOGY ,HALDIA

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CERTIFICATE
This is to certify that theis “TURBULENCE STUDY OF 2D -
MAGNETOHYDRODYNAMIC FLOW OVER SQUARE RIB IN A OPEN
CHANNEL” submitted by sujay kumar patar partial fulfillment of the
requirements for the award of Engineering with “ common Mechancal
engineering ” Specialization during session 2016-2018 Department of
Mechanical Engineering Haldia institute of technolog,haldia .
It is an authentic work carried out by him under my supervision and
guidance,To the bet of my knowledge the matter embodied in this
thesis has not been submitted to any University/Institute for award of
any Degree or Diploma.
Date
HALDIA(W.B) INDIA
Department of Mechanical Engineering
HALDIA INSTITUTE OF TECHNOLOGY
M.TECH 2016-2018
HEAD OF THE DEPARTMENT
………………………………
Prof. Goutam Bose
Associate Professor
………………………………
Mr. Manas kumar Bhokta
Haldia, india

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Acknowledgement
I express my deep sense of gratitude and indebtedness to my thesis
supervisor Mr. Manas kumar Bhukta Associate Professor, Department
of Mechanical Engineering for providing precious guidance, inspiring
discussions and constant supervision throughout the course of this
work. His timely help, constructive criticism, and conscientious
efforts made it possible to present the work contained in this thesis.
I express my sincere thanks to and Mr.Pritam Ghosh
Currently associate professor heritage institute of technology ,saltlake
kol-700107 wb.india. I am grateful to Prof. Goutam Bose, Head of the
Department of Mechanical Engineering for providing me the
necessary facilities in the department course for his timely help during
the course of work. I am also thankful to all the staff members of the
department of Mechanical Engineering and to all my well wishers for
their inspiration and help. And also to thanks my classmate’s .vineet
dube , m.tech( me), Pratush patra during the help my project.
I feel pleased and privileged to fulfill my parent’s ambition and I am
greatly indebted to them
for bearing the inconvenience during my M Tech. course.
Date Sujay Kumar Patar

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ABSTRACT
In current days of manufacturing we use cae software for more experimental set
up costand time involvement, this ansys codegives aprocimately real situation
results depending on good mesh capabilitis and valid boundary conditionds
setup
ANSYS FLUENT is a state of art computer program for modelling fluid flow
,heat transfer, magnetohydrodynamics and chemical reactions in complex
geometry,
OBJECTIVE of the thisis is flow over open chanel with 2 square rib study the
effect of mhd though without experiment we get the required magnetic field for
specific flow.
The results of CFD analyses are relevant in:
ConceptualConceptual studies of studies of new new designs designs
Detailed Detailed productproductdevelopment development
Troubleshooting Troubleshooting Redesign Redesign
CFD CFD analysis analysis complements complements testing and testing and
experimentation experimentation Reduces Reduces the total the total effort
effort required required in the in the experiment experiment design and data
design and data acquisition

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Contents page no
1.INTRODUCTION--------------------------------------------------------------------------------------7
2. OPEN CHANELFLOW-------------------------------------------------------------------------------8
2.CFD-----------------------------------------------------------------------------------------------------18
3. MAGNETO HYDRODYNAMICS------------------------------------------------------------------21
4.RESULTS.-----------------------------------------------------------------------------------------------23
6.CONCLUSION------------------------------------------------------------------------------------------29
5.REFERENCE---------------------------------------------------------------------------------------------31

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INTRODUCTION
Current day of CAD / CAM, CAE software is more use full for reducing
cost time and study of complex physics problem. Here we can see
the results of different aspect of then go to decisions for the specific
problem or situation.
Here in fluid flow practical data collection of a open channel air and
half-filled water is, very hazardous,,
So we depend on the simulation software and fluent solver
This solver has set of fluid flow differential equations, which.. it
solves input data to show graphical, animated results and further
improvement of parameter for required results,
The equations are solved by using numerical differential or integral
on cpu .
We relay about the model and the results, because we relay about
scientists model about fluid flow,
In nature most of the flow is turbulent , and in case of economical
flow of fluid we did not want large eddy over flow region,
So we reduced it by apply ing external magnetic effect to..
Reduce the intensity of turbulent flow of fluid. Here we study step by
step open channel flow,Magneto hydrodynamics and, about the
software results the software user need theoretical as well as
software interface experience to solve this type of problem

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OPENCHANNEL FLOW
General Open channel flow is a flow in a channel (conduit) that is not
completely filled and a free surfaceis formed between the flowing fluid
(water) and the air. The gravity force is the main force that drives such flows.
Most open channel flow correlations have been obtained from laboratory
small-scalemodels under uniform flow conditions. Significant attention has
been given to the study of open channel flow and its turbulence
characteristics. The flow in open channel can be classified, based on different
criteria such as developing, fully developed, uniform, non-uniform laminar,
turbulent, and so on. The existence of the free surfacealso allows the fluid to
self-select its configuration. Itis important to pay attention to uniform and
non-uniformopen channel flows, so this study mainly focuses on these two
types of open channel flows. An open channel flow can be classified as uniform
flow if the depth of flow (h) does not vary along the channel, and it is a
nonuniformflow if the depth varies along the channel. Depending on various
conditions, as well as the Reynolds number, open channel flow can also be
laminar, transitional, or turbulent.
2.2 Uniform& non-uniformopen channel flow A uniform flow is one in which
the velocity and depth remain constantover distance while in non-uniform
flow, both velocity and depth vary. Dueto changes in the channel cross-section
frompoint to point, uniformflow condition rarely occurs in either naturally
occurring or man-made channels. Uniform flow can occur only in a channel of
constantcross-section, roughness, and slopein the flow direction. Non-
uniformflow can occur in both man-madeand natural channel with variable
geometrical properties. The presenceof the pressuregradientis the main
causeof non-uniformity and has a global influence on the flow. Although
moderate non-uniformopen channel flows do actually exist, such cases are
usually assumed as uniformflow. At the river each bed slope can causethe
depth and velocity to vary fromupstream to downstream as a result, the water
surfacewill not be parallel to the bed. If the channel‟s cross-sectionalarea
decreases in the downstreamdirection, the flow is going to accelerate flow
with a positive velocity dUe /dx gradient and negative pressuregradient. On
the 14 other hand, if the channel‟s cross-sectionalarea increases, decelerating

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flow will be generated and negative velocity gradients and positivepressure
gradients will occur. Mathematically, pressurep(x) is linked to the free stream
velocity U(x) according to the Bernoulli's equation and the (1)
Accelerating flo w ( ) corresponds to a
negative or favourablepressuregradient, and decelerating flow (
)yields a positive or adversepressuregradientthat can lead to separation of
the boundary layer of the surface. Alternatively, if, , then uniform flow with
zero pressuregradientwill be achieved.
2.3 Reynolds averaged Navier stokes modeling The fluid flow equations that
are solved to characterize the flow structurein an open channel are the
Continuity and Reynolds-averaged Navier-Stokes (RANS) equations given in
tensor notation by
wherethe Reynolds averaged quantity is denoted by over bar. Here, ̅ and =
mean and fluctuating velocities in the direction, respectively with i = 1, 2.
Representing the stream-wisex, vertical z directions; xi = (x, z)  x; ui = (u, w); ̅
= ( ̅ ̅)  (u, w);  = kinematic viscosity; and p =kinematic pressure. Reynolds-
averaging the Navier-Stokes equation gives rise to unknown correlations
between the fluctuating velocities called Reynolds stresses defined by the
tensor ̅̅̅̅̅
. Physically these correlations, multiplied by density (), i.e. ̅̅̅̅̅
; is the
transportof momentum in the direction of Eqs. (2) and (3) can be solved for
the mean values of velocity, pressure, etc., when these turbulent correlations
can be related with mean velocity or pressure. This is called the closure
problem of turbulence modeling. These last terms are obtained from three
cross products of velocity fluctuations and provided additional stresses
developed due to turbulence. Hence they are called as turbulent shear stresses
or Reynolds stress and can be expressed as a stress tensor called Reynolds
stress tensor, written as

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(4)
where x  y  ,  and  z  are normalstresses and the other are shearing
stresses. Theadditional stresses areknown as apparent or virtual stresses of
turbulent flow or Reynolds stresses. Sincethese stresses areadded to the
ordinary viscous stresses in the laminar flow and have a similar influence on
the flow, it is often called eddy viscosity. In general, theseReynolds stresses far
outweigh the viscous stress in turbulent flow.
2.4 Reynolds stress distribution in open channel For a steady flow having zero
pressuregradientin x-direction (stream wise), the basic equations are
continuity equation and two components of Reynolds equations. The
continuity equation is automatically satisfied. The z-componentof Reynolds
equation (Eq. 3) gives an equation for the Reynolds stress w  w  . On the
other hand, the x-componentof Reynolds equation (Eq. 3) reduces to

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Classification of flow layers The flow of fluid over a solid boundary is classified
into numbers of flow layers. (Fig. 2.2) 1. Viscous sub-layer: A very thin layer just

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adjacent to the boundary. Theflow in this layer is fully laminar and the
turbulence is totally zero. 2. Transition-layer or Buffer-layer: In this layer both
viscous and turbulence effects exist. 3. Turbulent logarithmic-layer: A layer in
which the viscous shear stress is negligible and the shear stress is only due to
turbulence. 4. Turbulent outer-layer: In this layer, velocities are almost
constantbecause of the presence of large eddies, which producestrong mixing
of flow. This layer accounts approximately 80 % to 90 % of flow region.
By the modification of the mixing-length after Prandtl, the logarithmic velocity
profile is applied to both the buffer and outer-layers. Measurements and
computed velocities show reasonableagreement. On the other hand, in the
viscous sub-layers,boundary roughnessplays a significantrole on the velocity
distribution, which was firstinvestigated by Nikuradse(1933). Nikuradse
introduced the concept of equivalent roughness , called Nikuradse‟s
equivalent roughness. Based on the experimental data, the flow is classified as
follows: 1. Hydraulically smooth flow Re 5*  :Bed roughness is much smaller
than the thickness of viscous sub-layer  and hencewill not affect the velocity
distribution. 2. Hydraulically rough flow Re 70*  : Bed roughness is so large
that it produces eddies near the boundary and the viscous sub-layer no longer
exists. 3. Hydraulically transitionalflow 5 Re 70  *  : The velocity
distribution is affected by both bed roughness and viscosity. whereRe* =
particle Reynolds number, that is u*  / ; and u* = shear velocity   0.5  b 
and b  = bed shear stress. Fig. 2.3 presents the bed roughness on the flow
region.

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Velocity distribution The flow zoneover a boundary is characterized by the
two-layer: an inner-layer wherethe turbulence is directly affected by the bed
roughness and an outer-layer wherethe bed roughness indirectly influences
the flow. The inner-layer consists of viscous sub-layer and transition or
bufferlayer. On the other hand, the outer-layer is divided into turbulent
logarithmic-layer and turbulent outer-layers. Fig. 2.4 depicts the velocity
profiles in vertical direction whereas Fig 2.5 describes differentlayers over
smooth boundary. The velocity distributions in different layers are given in the
following subsections.

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2.6.1 Linear-law in viscous sub-layer In caseof smooth boundary, theviscous
shear stress (v) is constant and equal to the bed shear stress (0). Thatis v 0
dz du      (11) dz u du 2 *   (12)By integrating and using no slip
condition at the boundary, thatis u 0 z 0   , results u  u z  ~ * (13) whereu
u u* ~  . Therefore, there is a linear velocity distribution in viscous sub-layer
as shown in Fig. 2.5 and Eq. (23) is valid within the range 0  u* z   5.
Logarithmic-law in turbulent outer-layer In the turbulent outer layer, total
shear stress  is sameas the turbulent shear stress ( t  ). According to the
Prandtl‟s mixing length theory 2 2 t dz du l          (14) Putting l = Kz,
gives

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The American Society of Civil Engineers Task Committee (1963) reported that
for open channel roughness similar to that encountered in pipes, the
resistanceequations similar to those of pipe flows areadequate. For the flow
over smooth boundary, such as a plane bed surfacehaving median grain size
less than 0.25 mm, using equation (18) into equation (17) gives
Flow characteristics
In general, fluid flow can be distinguished in to two categories, laminar flow
and turbulent flow. Laminar flow takes place at relatively low velocity and is

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visualized as layered flow in which layers of fluid slide smoothly over each
other with different flow velocities withoutmicroscopic
mixing or exchange of fluid particles normalto the direction of flow. As the
flow velocity increases, the pattern of flow changes dramatically. Flow loses its
stability resulting in formation of eddy which expands throughoutthe flow
region. Such highly irregular, random and fluctuating flow is called turbulent
flow. The moststriking feature of this type of flow is that the velocity and the
pressureata fixed point in spacedo not remain constantat time but perform
very irregular fluctuations in high frequency. Flows in rivers and streams are
turbulent, in general. In turbulent flow, it is convenient to describethe
hydrodynamic quantities by separating the timeaveraged values from their
fluctuations or eddying motion. Such decomposition of an instantaneous value
of a hydrodynamic quantity is known as Reynolds decomposition.
Let the time averaged of velocity components be denoted by ̅ ̅ ̅and their
fluctuations by u‟, v‟, w‟ in the Cartesian coordinate system (x, y, z),
respectively; and also let the time-averaged pressureintensity and fluctuation
of pressurebedenoted by ̅and p‟ respectively. Then the instantaneous velocity
components (u, v, w) in the Cartesian coordinate system (x, y, z) and the
instantaneous pressureintensity p are given by

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Where to= any arbitrary time; and t1 = the time over which the average is
taken. The time t1is taken as a sufficiently long interval of time in order to
obtain the time independent quantities. The mean values are taken for a long
interval of time to be completely independent of time. Thus the time averages
of all quantities of fluctuations are equal to zero i.e.
In the courseof turbulent motion, the fluctuations u  ,v  ,w  influence the
mean motion u,v,win such a way that later exhibits an apparentincrease in
the resistanceto deformation, which is called as turbulent stresses or Reynolds
stresses.
The following relationship are known as the Reynolds conditions (Note: Bar
denotes time- averaging), written with two quantities, say F and G

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What is CFD? Computational Fluid Dynamics (CFD) is the science of
predicting:
_ Fluid flow
_ Heat and mass transfer
_ Chemical reactions and related phenomena by solving numerically the
set of governing mathematical equations.
Conservation of mass, momentum, energy, species, etc.
The results of CFD analyses are relevant in:
_ Conceptual studies of new designs

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_ Detailed productdevelopment
_ Troubleshooting
_ Redesign
CFD analysis complements testing and experimentation
_ Reduces the total effort required in the experiment design and data
Acquisition Typical applications include the prediction of jet breakup, the
motion of large
bubbles in a liquid, the motion of liquid after a dam break, and the steady or
transient tracking of any liquid-gas interface.
The following restrictions apply to the VOF model in ANSYS Fluent:
You must use the pressure-based solver. The VOF model is not available with
the density-based solver.
All controlvolumes must be filled with either a single fluid phase or a
combination of phases. The VOF model does not allow for void regions where
no fluid of any type is present.
Only one of the phases can be defined as a compressible ideal gas. There is no
limitation on using compressible liquids using user-defined functions.
Streamwise periodic flow (either specified mass flow rate or specified pressure
drop)cannot be modeled when the VOF model is used.
The second-orderimplicit time- formulation cannot be used with the VOF
explicit scheme.
The VOF formulation in ANSYS Fluent is generally used to compute a time-
dependent solution, but for problems in which you are concerned only with a
steady-state solution, it is possibleto perform a steady-state calculation. A
steady-state VOF calculation is sensible only when your solution is independent
of the initial conditions and there are distinct inflow boundaries for the
individual phases. Forexample, since the shape of the free surface inside a
rotating cup depends on the initial level of the fluid, such a problem must be
solved using the time-dependent formulation. On the other hand, the flow of
water in a channel with a region of air on top and a separate air inlet can be
solved with the steady-state formulation.
The VOF formulation relies on the fact that two or more fluids (or phases) are
not interpenetrating. For each additional phase that you add to your model, a
variable is introduced: the volume fraction of the phase in the computational
cell. In each control volume, the volume fractions of all phases sum to unity.
The fields for all variables and properties are shared by the phases and represent
volumeaveraged values, as long as the volume fraction of each of the phases is

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known at each location. Thus the variables and properties in any given cell are
either purely representative of one of the phases, or representative of a mixture
of the phases, depending upon the volume fraction values. In other words, if the
fluid’s volume fraction in the cell is denoted as , then the following three
conditions are
3.MAGNETOHYDRODYNAMICS
• Magnetohydrodynamics (MHD) has importance in both engineering and
biological :
• Some applications are :
• MHD generators,
• MHD flowmeters,
• plasma studies,
• cooling system of a nuclear reactor,
• geothermal energy extraction,
• blood flow problems.
• LORENTZFORCE & ITS APPLICATION

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 To analyze the effect of flow structure
 when a square rib is immersed in an Plain Open Channel Flow.
 MHD effect of different intensities on turbulence parameter
 when different strength of magnetic field is induced in flow over
square bluff body.

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PROBLEM STATEMENT
CFD SOLUTION METHODOLOGY
RESULTS:
velocity,
Pressure,turbulence intensity, turbulence kinetic energy,

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after applying H=50
RESULTS OF grapher 8 software plot
APPLYING MHD
TKE AFTER APPLYING MHD

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Future work
Compiled MHD work development done so far, related to fusion technology
Improvement of Reviewed the overall feasibility of electromagnetic flow
control (EMFC) concepts
Improvement of Experimental methodology for the measurement of Lorentz
forces on a small permanent magnet exposed to liquid metal flow in a
rectangular duct.
Improvement of Reviewed the overall feasibility of molten metal flow control.

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CONCLUTION
• Effect of single rib obstruction for the upstream positions is not
visible for too much distance.
Here we need experimental data (experimental setup) to validate
the software results

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REFERENCES
1. Nezu, I., Nakagawa, H., “Turbulence in open channel flow”. J. Hydr.
Eng. Vol : 112 (1993a), page 335-355
2. Nezu, I., Nakagawa, H., “Turbulence in Open Channel Flows”.
International Association for Hydraulic Research (1993b), A.A. Balkema
Publishers, Rotterdam
3. Nezu, I., Nakagawa, H., “Three dimensional structure of coherent
vortices generated behind dunes in turbulence free surface flows”. Proc.
5th Int. Symo. On Refined Flow Modeling and Turbulence
Measurements. (1993c), pp. 603-612
4. Morley NB, Smolentsev S, Barleon L, Igor R. Kirillov, Takahashi M.
“Liquid magnetohydrodynamics — recent progress and future directions
for fusion”. Fusion Engineering and Design. Vol : 51–52 (2000) page
701–713
5. Smolentsev S, AbdouM, Morley N, Ying A, Kunugi T. “Application of
the ‘‘K–’’modelto open channel flows in a magnetic field”.
International Journal of Engineering Science. Vol : 40 (2002) page 693–
711
6. Gao D, Morley NB, Dhir V. “Numerical study of liquid metal film flows
in a varying spanwise magnetic field”. Fusion Engineering and Design.
Vol : 63-64 (2002) page 369-374

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7. Smolentsev S, Morley N, Freezea B, Miraghaiea R , Nave JC, Banerjee S,
Ying A, AbdouM. “Thermofluid modeling and experiments for free
surface flows of low-conductivity fluid in fusion systems”. Fusion
Engineering and Design. Vol : 72 (2004) page 63–81
8. Takeuchi J, Satake S, Morley NB, Kunugi T, Yokomine T, Abdou MA.
“Experimental study of MHD effects on turbulent flow of Flibe simulant
fluid in circular pipe”. Fusion Engineering and Design Vol :83 (2008)
page 1082–1086
9. Schuster E, Luo L, Krstic M. “MHD channel flow controlin 2D Mixing
enhancement by boundary feedback”. Automatica Vol : 44 (2008) page
2498–2507
10.Xu C, Schuster E, Vazquez R, Krstic M. “Stabilization of linearized 2D
magnetohydrodynamic channel flow by backstepping boundary control”.
Systems & Control Letters Vol : 57 (2008) page 805–812
11.Braun EM, Lu FK, Wilson DR. “Experimental research in aerodynamic
control with electric and electromagnetic fields” Progress in Aerospace
Sciences Vol : 45 (2009) page 30–49
12.Pulugundla G, Heinicke C, Karcher C, Thess A. “Lorentz force
velocimetry with a small permanent magnet”. European Journal of
Mechanics B/Fluids Vol : 41 (2013) page 23–28
13.Leonardi S, Orlandi P, Djenidi L, Antoni RA. “Structure of turbulent
channel flow with square bars on one wall”. International Journal of Heat
and Fluid Flow Vol : 25 (2004) page 384–392
14.Feng KE, Ying-zheng LIU, Chun-yu JIN , Wei-zhe WANG,
“Experimental measurements of turbulent boundary layer flow over a
square-edged rib”. Conference of Global Chinese Scholars on
Hydrodynamics (2006) page 461 – 464
15.Ryu DN, Choi DH, Patel VC. “Analysis of turbulent flow in channels
roughened by two-dimensional ribs and three-dimensional blocks. Part II:
Heat transfer”. International Journal of Heat and Fluid Flow. Vol : 28
(2007) page 1112–1124
16.Pokrajac D, Campbell LJ, Nikora V, Manes C, McEwan I. “Quadrant
analysis of persistent spatial velocity perturbations over square-bar
roughness”. Exp Fluids Vol : 42 (2007) page 413–423

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17.Coleman SE; Nikora VI; McLean SR, Schlicke E. “Spatially Averaged
Turbulent Flow over Square Ribs”. J. Eng. Mech. Vol : 133(2007). Page
194-204
18.Tachie MF, Agelinchaab A, Shah MK. “Turbulent flow over transverse
ribs in open channel with converging side walls”. International Journal of
Heat and Fluid Flow 28 (2007) 683–707
19.Grundmann S, TropeaC. “Experimental damping of boundary-layer
oscillations using DBD plasma actuators”. International Journal of Heat
and Fluid Flow 30 (2009) 394–402
20.Arfaie A, Burns AD, Dorrell RM, J.T. Eggenhuisenc, D.B. Inghama,
W.D. McCaffrey b Optimised mixing and flow resistance during shear
flow over a rib roughened boundary International Communications in
Heat and Mass Transfer 58 (2014) 54–62

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