C_PB DISCI in mass transfer problem( sauter mean diameter)
 

Hello

the problem is about C_PB_DISCI and I am sure about it. but I dont know how to fix it
is there any way to calculate sauter mean diameter in Discrete phase in UDF?
here is the UDF


#include "udf.h"
#include "sg_pb.h"
DEFINE_MASS_TRANSFER(popbalance, c, t, from_index, from_species_index, to_index, to_species_index)
{
Thread *gas = THREAD_SUB_THREAD(t, to_index);
Thread *liq = THREAD_SUB_THREAD(t, from_index);
real m_lg, k_l, dal, usg, kappa, satc, a, satx, y, x, db, cl,na,db0,db1,db2,db3,db4,db5,db6;
m_lg=0;
y = C_YI(c, gas, to_species_index) / 32.04 / ( 1 / 60.1 - C_YI(c, gas, to_species_index) / 60.1 + C_YI(c, gas, to_species_index) / 32.04);
satx=0.8059 * y * y - 0.089 * y + 0.0555;
x= C_YI(c, liq, from_species_index) / 32.04 / ( 1 / 60.1 - C_YI(c, liq, from_species_index) / 60.1 + C_YI(c, liq, from_species_index) / 32.04);
k_l = 0.00011;
db0=0.009337;
db1=0.0157029;
db2=0.009337;
db3=0.0055518134;
db4=0.003301128;
db5=0.0019628625;
db6=0.001167125;
cl=15.2055;
a=6 *C_PB_DISCI(c,t,0)* C_VOF(c,gas)/ db0+6 *C_PB_DISCI(c,t,1)* C_VOF(c,gas)/ db1+6 *C_PB_DISCI(c,t,2)* C_VOF(c,gas)/ db2+6 *C_PB_DISCI(c,t,3)* C_VOF(c,gas)/ db3+6 *C_PB_DISCI(c,t,4)* C_VOF(c,gas)/ db4+6 *C_PB_DISCI(c,t,5)* C_VOF(c,gas)/ db5+6 *C_PB_DISCI(c,t,6)* C_VOF(c,gas)/ db6;
if (x > satx)
{
na = k_l * a * cl *(x - satx);
m_lg= 32.04 * na;
C_UDMI(c,t,0)=m_lg;
}
return (m_lg);
}





The error



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Node 0: Process 73088: Received signal SIGSEGV.

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Node 3: Process 73192: Received signal SIGSEGV.

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Node 4: Process 73208: Received signal SIGSEGV.

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Node 5: Process 73220: Received signal SIGSEGV.

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Node 6: Process 73236: Received signal SIGSEGV.

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Node 7: Process 73248: Received signal SIGSEGV.

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Node 1: Process 73164: Received signal SIGSEGV.

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Node 2: Process 73180: Received signal SIGSEGV.

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MPI Application rank 0 exited before MPI_Finalize() with status 2
The fl process could not be started.

You're using User-Defined Memory (UDM), are you sure you've remembered to enable slots for this UDM?

yes I did
I runned the case without (C_PB_DISCI) and there were no problem.
I am sure that the problem is with C_PB_DISCI

The SIGSEGV error suggests you're trying to access a variable / memory space which has not been allocated. I've not used the Sauter mean diameter feature but is it valid to use seven indices from "C_PB_DISCI"? Try only using the first one with an index of 0 and check the usage in the Fluent documentation.

I tried it didnt work
 

It didn't work.
C_POP_DISCI gives the fraction of a particular bubble size in the domain (in case you are not familiar with the discrete population balance model):confused::confused::confused:

Are any of the other population balance variables working in your UDF? For example the weight: C_PB_QMOMI_W(c,t,i). If these variables/macros yield the same error then perhaps the population balance model has not been enabled or setup correctly? Have these variables worked in the past or are there any working examples available?

I am not using QMOMI model, C_PB_DISCI_PS also did not work.
If I dont use C_PB_DISCI_PS or C_PB_DISCI , the case doesnt have any problem, and the bins fractions of discrete pop balance model can be checked by contours, the only problem is when I use them.
Do I have to use any loop?

Hi Majid,

I think the problem is the thread you are using in C_PB_DISCI, t, which is mixture thread. To solve it use C_PB_DISCI(c,gas,i), where gas is the thread to gas phase.

Hope it solves it for you

I have finished this and I have used sauter mean diameter,
It is not possible to use C_PB_SICI in mass transfer.:(

hello，dose anyone know how to export sauter mean diameter changing with time？

I would use the UDF DEFINE_EXECUTE_AT_END. With C_PHASE_DIAMETER(c,t) you get the Sauter diameter and you can write the values in a text file.