how to get such mass fraction
 

hello. now, i am modeling a heat transfer flow. i want to get the mass fraction of the fluid in a certain temperature range. how can i deal with this problem? thanks.

Re: how to get such mass fraction
 

the follwing udf can be run in interpreted mode and computes the fluid mass within tmin and tmax (K).

good luck rom

#include "udf.h"

#define Tmin 1200

#define Tmax 1500

DEFINE_ON_DEMAND(get_fraction)

{

Domain *d;

cell_t c;

Thread *t;

real mf,mft;

mf=0;

mft=0;

d = Get_Domain(ROOT_DOMAIN_ID);

thread_loop_c(t,d)

{

begin_c_loop(c,t)

{

if((C_T(c,t)>=Tmin) && (C_T(c,t)<=Tmax)) mft += C_R(c,t)*C_VOLUME(c,t);

mf += C_R(c,t)*C_VOLUME(c,t);

}

end_c_loop(c,t)

}

printf("\nfluid mass = %f kg",mf);

printf("\nfluid mass within temperature range = %f kg",mft);

}

Re: how to get such mass fraction
 

oh, thank you, rom. this really help me a lot

Re: how to get such mass fraction
 

hi, rom. i try to use this udf on my computer.it can be compiled successfully. but, when i try to execute it from "execute on demand" panel, there is no reaction at all. i want to know where is the result printed to? thanks!

Re: how to get such mass fraction
 

Sometime Fluent doenst get the printf command right. I tested the udf on my machine (WinXP Fluent6.2) and it worked. You can substitute the "printf" with "Message". This usually solves the problem but then the udf will not longer run in interpreted mode so you will have to compile it first.

good luck rom