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Old   January 14, 2013, 08:21
Default velocity profile
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Rohit kumar Mittal
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Dear friends,
i am trying to plot the velocity profile for a flowing fluid at cross section of open channel using fluent. I have done modelling as well as meshing. Beside these in fluent, i have switched on gravity, in models, i have chosen volume of fluid model>open channel flow, checked energy equation and used k-epsilon (2 eqn.).
I have given water as primary and air as secondary phases. Besides these all are set as default. Still i am not getting the correct velocity profile. please help me. I got stuck since a long time.
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Old   January 18, 2013, 17:16
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Rohit kumar Mittal
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Dear friends,
is there no one who is able to help me?
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Old   January 19, 2013, 05:31
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It is an easy problem.
Which boundary conditions have you use? There is no need to enable energy equation.
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Old   January 19, 2013, 06:29
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Sir,
boundary conditions are as follows:
(1)At velocity inlet-
v=0 at inlet
initial gauge pressure= 0
turbulence specification method- Intensity and hydraulic diameter
temperature= 300K

(2)At pressure outlet-
back-flow direction specification method- Normal to boundary
turbulence specification method- Intensity and hydraulic diameter
temperature= 300K

checked the open channel in multiphase tab where-
pressure specification method- from neighbouring cell
bottom level i selected which is at outlet side.

(3)Stationary walls-
wall motion- stationary wall
shear condition- no shear
wall roughness- roughness constant= 0.5
roughness height = 0
wall adhesion-
contact angle(air-water)= 90 degree

All remaining conditions are default.
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Old   January 19, 2013, 06:55
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in open channels you should use outflow instead of pressure outlet.
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Old   January 20, 2013, 09:02
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As per your saying, i used outflow instead of pressure outlet.
What is flow rate weighting?
Although i took its value equal to one.
But still i am not getting the correct velocity profile.
Sir, if you have already done it before, kindly mail me the way in which i should proceed at rkmittal1108@gmail.com
I will be very thankful to you.
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Old   January 20, 2013, 10:08
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Set it 1 if you have just one outlet. Else you should define fraction of flow that gets out of the domain from each outlet.
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