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UDF Define_Init velocity profile

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Old   June 9, 2013, 07:06
Default UDF Define_Init velocity profile
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Thomas Crepon
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Hi everyone,

I really need your help for a scholar modeling. I want to create as an initial condition on inlet, a velocity profile quite simple : if y<2.5 then U=0, else U=2*y.

The problem is that I never used C language in my life and so as a complete rookie I'm quite lost...

Below you'll find what I've tried to write by copying other examples found on the net.

Thanks a lot for every little help you could give me (and sorry for my english)

Best Regards
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File Type: c udfinit.c (282 Bytes, 17 views)
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Old   June 14, 2013, 21:03
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Mahboobe Mahdavi
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do you still need help? I can help you
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Old   June 19, 2013, 01:19
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Thomas Crepon
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It's a bit too late for my scholar deadline but nevertheless, I'm really interested to know how should I have done this ! So I welcome your help if it's still possible.
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Old   June 19, 2013, 13:45
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Mahboobe Mahdavi
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I guess the problem is due to this part:
y=F_CENTROID(y,f,t);

you need to define real y[ND_ND];
then
F_CENTROID(y,f,t);
so your x coordinate will be y[0] and y coordinate will be y[1]
--------------------------------------------------------------
#include "udf.h"
DEFINE_INIT(udfinit,d)
{
cell_t c;
Thread *t;
real x[ND_ND];
real y;

/* loop over all cell threads in the domain */
thread_loop_c(t,d)
{
/* loop over all cells */
begin_c_loop_all (c,t)
{
F_CENTROID(x,c,t);
y=x[1]
if y>2.5
C_U(c,t)=0

else
C_U(c,t)=2*y
}
end_c_loop_all(c,t)
}
}
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