[CMIUCBS]

Hi everyone.
I'm Trying to simulate a boiling flow with water based nanofluid as the Primary phase and vapor as the secondary phase; therefore I'm trying to write a define property and define specific heat udf for the primary phase.


The problem is that after I gave the code to fluent and initialized, I get this error:

"received signal sigsegv fluent"


I read somewhere that it's because the code is written wrong.

here is my udf:


#include"udf.h"


DEFINE_PROPERTY(conductivity, c, thread)
{
Thread *thread_liq = THREAD_SUB_THREAD(thread,0);
Thread *thread_vap = THREAD_SUB_THREAD(thread,1);



real k_eff,ks,kf,kh,kl,Tw,vf;



Tw = C_T(c,thread_liq);


vf=0.001; /*volume fraction of the nano particles */
kl=0.664;
kh=0.5928;
kf=(((kh-kl)/70)*(Tw-473.15)+kl); /*Conductivity Base Fluid*/

ks=32.9; /*Conductivity Nanoparticle*/

k_eff=(((1-vf)*(ks+2*kf)+3*vf*(ks))/((1-vf)*(ks+2*kf)+3*vf*(kf)))*kf;

return k_eff;
}



DEFINE_SPECIFIC_HEAT(specficheat,T, Tref, h, yi)
{
cell_t c;
Thread *thread;
Thread *thread_liq = THREAD_SUB_THREAD(thread,0);
Thread *thread_vap = THREAD_SUB_THREAD(thread,1);
real cp_f,cp_nf,cp_s,ro_f,ro_s,ro_nf,roh,rol,ch,cl,Tw,v f;
Tw = C_T(c,thread_liq);
vf=0.001; /*volume fraction of the nano particles */
rol=864.7;
roh=770.6;
ro_f=(((roh-rol)/70)*(T-473.15)+rol);
ro_s=6310;
ro_nf=(1-vf)*(ro_f)+vf*(ro_s);
cl=4494;
ch=5067;
cp_f=(((ch-cl)/70)*(T-473.15)+cl);
cp_s=550.3;
cp_nf=(((1-vf)*(ro_f*cp_f)+vf*(ro_s*cp_s))/((1-vf)*(ro_f)+vf*(ro_s)));

*h = cp_nf*(T-Tref);
return cp_nf;
}






can anybody help me?

[pakk]

To find out where the problem is, you should simplify your UDF. Remove lines until you find the line that gives the error.

[CMIUCBS]

thank you for your reply.
I had simplified the code and I think the problem is in the way I use phase threads in my code.
I want to use my primary phase cell temperature in the code and i simplified it to this but it's still wrong.
can you help me figure out where i'm writing it wrong? I think it's the bold words that causing the problem.

Here is my code:


#include"udf.h"

DEFINE_PROPERTY(density, c, thread)
{
real ro_nf,ro_f,ro_s,roh,rol,vf;
real Tw;
Thread *thread_liq;
thread_liq = THREAD_SUB_THREAD(thread,0);
Tw = C_T(c,thread_liq);
vf=0.001; /* volume fraction of the nano particles */
rol=864.7;
roh=770.6;
ro_f=(((roh-rol)/70)*(Tw-473.15)+rol);
ro_s=6310;
ro_nf=(1-vf)*(ro_f)+vf*(ro_s);

return ro_nf;
}

[pakk]

You should simplify to the extreme, see below. Do both give errors?

#include"udf.h"

DEFINE_PROPERTY(density, c, thread)
{
Thread *thread_liq;
thread_liq = THREAD_SUB_THREAD(thread,0);
}

#include"udf.h"

DEFINE_PROPERTY(density, c, thread)
{
real Tw;
Thread *thread_liq;
thread_liq = THREAD_SUB_THREAD(thread,0);
Tw = C_T(c,thread_liq);
}

[CMIUCBS]

Thank You for your respond. I managed to find the problem and rewrite the code.
The problem was that i didn't properly introduced the domain and sub threads in the udf.

Here's the code if anyone had a similar problem in the future:


#include"udf.h"

DEFINE_PROPERTY(density, c, thread)
{
Domain *mixture_domain = Get_Domain(1);
Thread *mixture_thread = Lookup_Thread(mixture_domain,8);
Thread *Primary_phase_thread = THREAD_SUB_THREAD(mixture_thread,0);
Thread *Secondary_phase_thread = THREAD_SUB_THREAD(mixture_thread,1);


real ro_nf,ro_f,ro_s,roh,rol,vf;
real Tw;
Tw = C_T(c,Primary_phase_thread);
vf=0.001; /* volume fraction of the nano particles */
rol=864.7;
roh=770.6;
ro_f=(((roh-rol)/70)*(Tw-473.15)+rol);
ro_s=6310;
ro_nf=(1-vf)*(ro_f)+vf*(ro_s);

return ro_nf;
}

[ustbdynamic]

Dear friend,
what's the meaning of the number 8 in Lookup_Thread(mixture_domain, 8); it is a cell zone ID or phase ID.

thank you very much.

Originally Posted by CMIUCBS

Thank You for your respond. I managed to find the problem and rewrite the code.
The problem was that i didn't properly introduced the domain and sub threads in the udf.

Here's the code if anyone had a similar problem in the future:


#include"udf.h"

DEFINE_PROPERTY(density, c, thread)
{
Domain *mixture_domain = Get_Domain(1);
Thread *mixture_thread = Lookup_Thread(mixture_domain,8);
Thread *Primary_phase_thread = THREAD_SUB_THREAD(mixture_thread,0);
Thread *Secondary_phase_thread = THREAD_SUB_THREAD(mixture_thread,1);


real ro_nf,ro_f,ro_s,roh,rol,vf;
real Tw;
Tw = C_T(c,Primary_phase_thread);
vf=0.001; /* volume fraction of the nano particles */
rol=864.7;
roh=770.6;
ro_f=(((roh-rol)/70)*(Tw-473.15)+rol);
ro_s=6310;
ro_nf=(1-vf)*(ro_f)+vf*(ro_s);

return ro_nf;
}

[AlexanderZ]

its zone ID (comes from the logic of code which I can see)

[CMIUCBS]

Originally Posted by ustbdynamic

Dear friend,
what's the meaning of the number 8 in Lookup_Thread(mixture_domain, 8); it is a cell zone ID or phase ID.

thank you very much.

It's the fluid domain ID which you can obtain in Cell Zone Condition. you have to change it for your case.