# inflow velocity distribution is given by the Poiseuille flow

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 June 12, 2020, 23:53 inflow velocity distribution is given by the Poiseuille flow #1 Senior Member   Weiqiang Liu Join Date: Feb 2018 Posts: 278 Rep Power: 8 Hi all, I am trying to reproduce results in literature. For inlet velocity boundary condition setting, the author says "The inflow velocity distribution is given by the poiseuille flow" I know poiseuille flow is a parabolic velocity distribution from central to wall. I am wondering how can I set the parameters of this parabolic distribution if I know the central velocity of inflow? Best regards Weiqiang

June 14, 2020, 12:05
#2
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mCiFlDk
Join Date: Feb 2020
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Quote:
 Originally Posted by Weiqiang Liu Hi all, I am trying to reproduce results in literature. For inlet velocity boundary condition setting, the author says "The inflow velocity distribution is given by the poiseuille flow" I know poiseuille flow is a parabolic velocity distribution from central to wall. I am wondering how can I set the parameters of this parabolic distribution if I know the central velocity of inflow? Best regards Weiqiang
Hi weiqiang,

To make that, you've to use a User Defined Function, more specifically a DEFINE_PROFILE one. Luckily, ANSYS has a very similar function in its manual to imitate this problem you're trying to simulate.

Code:
```/***********************************************************************
vprofile.c
UDF for specifying steady-state velocity profile boundary condition
************************************************************************/

#include "udf.h"

{
real x[ND_ND]; /* this will hold the position vector */
real y, h;
face_t f;

h = 0.016; /* inlet height in m */

{
y = 2.*(x[1]-0.5*h)/h; /* non-dimensional y coordinate */
}
}```

Code got from: https://www.afs.enea.it/project/nept...df/node243.htm

If you look a bit deeper in the manual, this will not be very complicated since the function is that and you only have to modify the parameters for your specific case.

Regards.

 Tags inlet boundary, poiseuille flow