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Time-Varying Inlet Velocity

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Old   January 27, 2010, 12:25
Default Time-Varying Inlet Velocity
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I'm trying to impose time-varying velocity at the inlet. Can someone guide me on how to impose the bc ?

Thanks.
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Old   January 27, 2010, 17:00
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Use a UDF - you will find an example of a an unsteady velocity boundary condition in the Fluent UDF manual.

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Old   January 27, 2010, 17:18
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thanks for the reply.

for example: if i want v(t) = 0.1*t for 0< t < 1 at the inlet,
is the following UDF correct ?

Code:
#include "udf.h"

DEFINE_PROFILE(transient_velocity, thread, position)
{

  float t, velocity;
  face_t f;

  t = RP_Get_Real("flow-time");

  velocity = 0.1*t;

  begin_f_loop(f, thread)
  {
   F_PROFILE(f, thread, position) = velocity;
  }
  end_f_loop(f, thread)

}
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Old   January 27, 2010, 20:25
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Looks OK (I didn't tested your code in Fluent), however if you want to apply this only for 0< t < 1 ... you've missed a test condition.

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Old   September 24, 2010, 16:26
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dear cfdfsi,

I was using your UDF to impose a time varying velocity inlet on a 3D cylinder. However, I'm not getting a plug profile with it.

Did anything similar happened to you?




Thanks!
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