UDF for energy source
 

Hello everyone,
I am writing UDF for energy source.I need to retrieve subdomain for primary ans secondary phase using THREAD_SUB_THREAD.
I have gone through UDF manual but i,m having some problem in implementation part. Can someone help me?

Thanks a lot...

share what you've done and we can see possible faults.

UDF for energy source
 

Thanks for reply..


#include "udf.h"
#define LH 2250.0
#define T_SAT 373.15
DEFINE_SOURCE(eng_eqn,cell,thread,dS,eqn)
{
real x[ND_ND];
real con, source;
begin_c_loop_all(cell,thread)
{
C_CENTROID(x,cell,thread);
Thread *thread, *thread;
thread = THREAD_SUB_THREAD(cell,thread);
thread = THREAD_SUB_THREAD(cell,thread);
if (C_T(cell, thread) > T_SAT)
{
con = -0.1*C_VOF(cell,thread)*C_R(cell,thread)*((C_T(cell ,thread)-T_SAT)/T_SAT)*x[1];
source = con*LH;
}
else if (C_T(cell, thread) < T_SAT)
{
con = 0.1*C_VOF(cell,thread)*C_R(cell,thread)*((T_SAT-C_T(cell,thread))/T_SAT)*x[1];
source = con*LH;
}
}
end_c_loop_all(cell,thread)
dS[eqn] =0.1*C_VOF(cell,thread)*C_R(cell,thread)/T_SAT;
return source;
}

Have a look in this website https://www.sharcnet.ca/Software/Flu...udf/node99.htm

Search for the Phase-Level Thread Pointer ( THREAD_SUB_THREAD). You will see that it defines for the primary phase as 0, but you can also define other fazes as different integers.

In addition to that, you are also pointing and defining thread 2 times (and this value is already retrieved from the source macro).

i have modified it as:


#include "udf.h"
#define LH 2250.0
#define T_SAT 373.15
DEFINE_SOURCE(eng_source,cell,thread,dS,eqn)
{
real x[ND_ND];
real con, source;
cell_t gas, liq;
begin_c_loop_all(cell,thread)
{
C_CENTROID(x,cell,thread);

liq = THREAD_SUB_THREAD(liq,0);
gas = THREAD_SUB_THREAD(gas,1);
if (C_T(cell, liq) > T_SAT)
{
con = -0.1*C_VOF(cell,liq)*C_R(cell,liq)*((C_T(cell,liq)-T_SAT)/T_SAT)*x[1];
source = con*LH;
}
else if (C_T(cell, gas) < T_SAT)
{
con = 0.1*C_VOF(cell,gas)*C_R(cell,gas)*((T_SAT-C_T(cell,gas))/T_SAT)*x[1];
source = con*LH;
}
}
end_c_loop_all(cell,thread)
dS[eqn] =0.1*C_VOF(cell,thread)*C_R(cell,thread)/T_SAT;
return source;
}


But, after i interpret it at the first iteration it shows error as
Error: received a fatal signal (Segmentation fault).

you are defining "gas" and "liq" as cells and later defining it as sub threads...

Ohh..
Thank you. You have been very helpful.
I've also written a mass transfer udf. Would you please give it a look?

#include "udf.h"

DEFINE_MASS_TRANSFER(liq_gas_source, cell, thread, from_index,from_species_index,to_index, to_species_index)
{
real m_lg;
real T_SAT = 373.15;
Thread *gas, *liq;
gas = THREAD_SUB_THREAD(thread, from_index);
liq = THREAD_SUB_THREAD(thread, to_index);
m_lg = 0.0;
if (C_T(cell, liq) > T_SAT)
{
m_lg = -0.1*C_VOF(cell,liq)*C_R(cell,liq)*(C_T(cell,liq)-T_SAT)/T_SAT; /* Evaporating*/
}
else if (C_T(cell, gas) < T_SAT)
{
m_lg = 0.1*C_VOF(cell,gas)*C_R(cell,gas)*(T_SAT-C_T(cell,gas))/T_SAT; /* Condensing */
}
return (m_lg);
}


Do i need to use #include "sg_mphase.h"?

i cant check all udfs by just looking it. you need to try it on you pc, see if it returns any error, or if the values it is returning are the ones you are expecting.

about the sg_mpahse.h library, i do not know.check the udf.h and see either it is already included or not in it.