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Old   January 21, 2008, 11:19
Default Set velocity in BC
  #1
Xavi
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Hi! I have a 2D model and I would like to fix the components of velocity in one of the edges as follows: Vy=0 Vx= not fixed (is computed by FLUENT).

Does anyone know what kind of BC should I use? Many thanks Xavi

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Old   January 21, 2008, 12:02
Default Re: Set velocity in BC
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Leverkin
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You can write a simple UDF tha access the edge you want and set the Vy = 0. There is an access macro command that allows you to do that: C_U(c,t) and C_V(c,t). You can try that.
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Old   January 22, 2008, 07:50
Default Re: Set velocity in BC
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Xavi
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Thanks! I am trying to find out more info about UDFs, What does the c mean? is it a constant?. Do you know exactly what should the text of the UDF be? thanks
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Old   January 22, 2008, 08:40
Default Re: Set velocity in BC
  #4
Leverkin
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"c" stands for cell, "f" for face and "t" for thread.

It will look like that

include "udf.h"

DEFINE_PROFILE(velocity,t,i) {

real r; cell_t c;

begin_c_loop(c,t)

{

C_V(c,t) = 0 }

end_c_loop(c,t)

}

try this. It will probably works.

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Old   January 24, 2008, 07:52
Default Re: Set velocity in BC
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Xavi
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Mnay thanks! I found out an easier way to do that: impose the boundary condition: "symmetry" and then the Vy=0 and Vx is computed. Cheers, xavi
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