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Old   August 9, 2011, 11:12
Default Boundary Condition
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Hi Foamer's
I want Simulate Viscoelastic's fluid in geometry that can see in attach file.
my problem is boundary condition.
my geometry produced by 3 rectangular that can see.
first part and third part have similar B.C's
for the first & third part:
up wall:symmetry plan
bottom wall:fixed wall
inlet for the first part,outlet for third part
and for the right and left wall what should i do?
and for the second part what should i do?(B.C's)
can i set all wall's , Fixed Wall?
Please help me.
Thank you,
Usef
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Old   August 9, 2011, 14:49
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I'm waiting for your kind response .....
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Old   August 10, 2011, 18:31
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If there isn't going to be any significant variation in the z-direction, then you can save yourself a lot of time by making the mesh only one cell deep in that direction and making the boundaries whose normal is the z direction into empty boundary conditions. Otherwise the BC will be some kind of zero-gradient conditions depending if you have inflow/outflow.
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Old   August 10, 2011, 20:56
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Quote:
Originally Posted by mturcios777 View Post
If there isn't going to be any significant variation in the z-direction, then you can save yourself a lot of time by making the mesh only one cell deep in that direction and making the boundaries whose normal is the z direction into empty boundary conditions. Otherwise the BC will be some kind of zero-gradient conditions depending if you have inflow/outflow.
Thank
But I should solve in 3D,
and for wall Bc's have opinion?
I must See Secondary Flow In Inlet & Outlet,if we Solve 2D, cant!
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Old   August 11, 2011, 15:03
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I don't know anything about visco-elastic simulations and don't know if there any any special considerations to make at the walls. U=0 on stationary walls and p is zero-gradient.

What do you mean by secondary flow? With more information on what that means physically in your case I might be able to suggest something to you.
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Old   August 12, 2011, 10:55
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Hi Dear
in fact,I want Simulate Vortex,
then simulation we can see stream line and secondary Flow.
boundary condition for stress,U,P is my problem
and i dont know how can i see vortex and Stream line in Open foam,
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Old   August 12, 2011, 13:50
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Do you mean you want to simulate the vortex in the square cavity? I think you should still be able to do this in 2D. Did you look at the tutorial for lid-driven cavity flow?

http://www.openfoam.com/docs/user/cavity.php

My suggestions for boundary conditions are.
Your BC's seem fine, just remember that you still need to specify values when you use the inlet, outlet, inletOutlet or outletInlet conditions. You can read more about OpenFOAM's boundary conditions here:

http://www.openfoam.com/docs/user/boundaries.php

Finally, to be able to visualize the vortex and streamlines, you need to use ParaFoam. The lid-driven cavity flow tutorial will give you more information.
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