[abdoli]

hi guys
i am new in using udf. i am modeling nucleate boiling and i have some problem in that. i am writing a udf to use DEFINE_SOURCE for a part of one boundary (zone-ID is 3) of my model as below. (my model is a simple rectangular).
#include "udf.h"
DEFINE_SOURCE(VOF_source1, c, t, dS, eqn)
{
real xc[ND_ND], c1x, c1y, source;
face_t f;
cell_t c,c0;
Domain *domain=Get_Domain(1);
Thread *t0,*t=Lookup_Thread(domain,3);
c0 = F_C0(f,t);
t0 = THREAD_T0(t);
C_CENTROID(xc,c0,t0);
c1x=xc[0];
c1y=xc[1];
if (0.01<c1y && c1y<0.03)
{
source =0.055;
dS[eqn] =0;
return source;
}
}
it works but it seems that source term exists in all of domain, not only in the part of the specified boundary and the part that is defined by if statement.
what is wrong? your guide will be very helpful for me.
if more information in needed, i will send.

best regards

[AlexanderZ]

Originally Posted by abdoli

hi guys
i am new in using udf. i am modeling nucleate boiling and i have some problem in that. i am writing a udf to use DEFINE_SOURCE for a part of one boundary (zone-ID is 3) of my model as below. (my model is a simple rectangular).
#include "udf.h"
DEFINE_SOURCE(VOF_source1, c, t, dS, eqn)
{
real xc[ND_ND], c1x, c1y, source;
face_t f;
cell_t c,c0;
Domain *domain=Get_Domain(1);
Thread *t0,*t=Lookup_Thread(domain,3);
c0 = F_C0(f,t);
t0 = THREAD_T0(t);
C_CENTROID(xc,c0,t0);
c1x=xc[0];
c1y=xc[1];
if (0.01<c1y && c1y<0.03)
{
source =0.055;
dS[eqn] =0;
return source;
}
}
it works but it seems that source term exists in all of domain, not only in the part of the specified boundary and the part that is defined by if statement.
what is wrong? your guide will be very helpful for me.
if more information in needed, i will send.

best regards

Hello

DEFINE_SOURCE(VOF_source1, c, t, dS, eqn) macros already has built in loop over all cells-threads (VOF_source1, c, t, dS, eqn)

I'm suggesting you to use flag UDMI variable for the region, you are interested in.

#include "udf.h"
DEFINE_SOURCE(VOF_source1, c, t, dS, eqn)
{
   real xc[ND_ND], c1x, c1y, source;
   face_t f;
   cell_t c,c0;
   Domain *domain=Get_Domain(1);
Thread *t0,*t=Lookup_Thread(domain,3);
   c0 = F_C0(f,t);
   t0 = THREAD_T0(t);
   C_CENTROID(xc,c0,t0);
    c1x=xc[0];
    c1y=xc[1];
if (C_UDMI(c,t,0) >0 )
{
if (0.01<c1y && c1y<0.03)
{
    source =0.055;    
}
}else{source= 0.0;}
dS[eqn] =0;
return source;
}

Now when you initialized your simulation go to Patch... and put value 1 for UDMI_0 in the region you want

Do not forget to change the number of UDMs in Fluent GUI from 0 to 1

Best regards

[abdoli]

dear AlexanderZ
thanks for your reply. now i have one domain in my model. is it needed to separate region that should be patched (near boundary) at first? if yes, how i can do that?