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Old   November 25, 2013, 12:39
Default using C_VOF
  #1
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anonymous
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Dear Colleagues,

I need your help in using C_VOF macro.
In my project I need to capture the interface between two fluids (C_VOF=0.5) and assign to the cells on the interface the values I would like to (for example temperature).

The problem is that I cannot select the cells with C_VOF = 0.5 . The udf works if I select cells with C_VOF=1 or 0, but not with the interface.

How could I make it?

Here is my udf

#include "udf.h"
#include "sg_mphase.h"

DEFINE_ADJUST(scan3,d)
{
Thread *t;
Thread **pt;
cell_t c;
int zone_ID=2;
Thread *mixture_thread = Lookup_Thread(d,zone_ID);
pt = THREAD_SUB_THREADS(mixture_thread);
thread_loop_c(t,d)
{
begin_c_loop(c,t)
if (C_VOF(c,pt[1])==0.5) /* pt0 - air, pt1 - ls */
{
C_T(c,pt[1])=1500;
}
end_c_loop(c,t)
}
}
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Old   November 26, 2013, 03:12
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Max
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You are searching for cells with vof == 0.5 exactly. Maybe there is no cell which matches this strict requirement but certainly there will be some with 0.49<C_VOF<0.51.

Cheers
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Old   November 26, 2013, 04:54
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anonymous
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Thank you very much for your reply!

No, this cells don't exist too.
However, it works if I specify the range of C_VOF from 0.000001 to 0.999999 . But also not always as well... it somehow depends on time-step size and number of iterations per step.

For example if I set up time-step 0,05 sec and 5 iterations per step then it works, but if i set up time-step 0.05 and 20 iterations it doesn't.

... and this doesn't make any sense to me. Any ideas?

Quote:
Originally Posted by coglione View Post
You are searching for cells with vof == 0.5 exactly. Maybe there is no cell which matches this strict requirement but certainly there will be some with 0.49<C_VOF<0.51.

Cheers
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