[hitzhwan]

When I use the following phase change code,I use a gradient of the volume fraction, I do not know whether it is right. When I import it into the fluent, it does not have any error. But when it run, the fluent give the following errors, who can help me find the problem and revise it, thank you.

The below is the error note:

Divergence detected in AMG solver: pressure correction
Error at host: floating point exception
Error at Node 0: floating point exception

Error: floating point exception


The codes：

#include "udf.h"
#include"sg_mphase.h"
#define LAT_HT 193260
#define C1 0.1
#define MW 0.018
#define RR 8.314
#define PI 3.1415926
#define T_SAT 293.15


DEFINE_SOURCE(liq_src, cell, sec_th, dS, eqn)
{
Thread *mix_th, *pri_th;
real m_dot_l;
real pp;
mix_th = THREAD_SUPER_THREAD(sec_th);
pri_th = THREAD_SUB_THREAD(mix_th, 0);



if(C_T(cell, mix_th)>=T_SAT)
{

m_dot_l = -2*C1/(2-C1)*sqrt(MW/2/PI/RR)*(C_R(cell, pri_th)*LAT_HT*fabs(T_SAT-C_T(cell,sec_th)))/pow(T_SAT,1.5)*abs(C_VOF_G(cell, pri_th));

dS[eqn] = -2*C1/(2-C1)*sqrt(MW/2/PI/RR)*(C_R(cell, pri_th)*LAT_HT*fabs(T_SAT-C_T(cell,sec_th)))/pow(T_SAT,1.5);
}
else
{
m_dot_l = 2*C1/(2-C1)*sqrt(MW/2/PI/RR)*(C_R(cell, pri_th)*LAT_HT*fabs(T_SAT-C_T(cell,mix_th)))/pow(T_SAT,1.5)*abs(C_VOF_G(cell, pri_th));
dS[eqn] = 0.;
}
return m_dot_l;
}

DEFINE_SOURCE(vap_src, cell, pri_th, dS, eqn)
{
Thread * mix_th, *sec_th;
real m_dot_v;
real pp;

mix_th = THREAD_SUPER_THREAD(pri_th);
sec_th = THREAD_SUB_THREAD(mix_th, 1);


if(C_T(cell, mix_th)>=T_SAT)
{
m_dot_v = 2*C1/(2-C1)*sqrt(MW/2/PI/RR)*(C_R(cell, pri_th)*LAT_HT*fabs(T_SAT-C_T(cell,mix_th)))/pow(T_SAT,1.5)*abs(C_VOF_G(cell, pri_th));
dS[eqn] = 0.;
}
else
{
m_dot_v = -2*C1/(2-C1)*sqrt(MW/2/PI/RR)*(C_R(cell, pri_th)*LAT_HT*fabs(T_SAT-C_T(cell,mix_th)))/pow(T_SAT,1.5)*abs(C_VOF_G(cell, pri_th));
dS[eqn] = -2*C1/(2-C1)*sqrt(MW/2/PI/RR)*(C_R(cell, pri_th)*LAT_HT*fabs(T_SAT-C_T(cell,mix_th)))/pow(T_SAT,1.5);
}
return m_dot_v;
}


DEFINE_SOURCE(enrg_src, cell, mix_th, dS, eqn)
{
Thread *pri_th, *sec_th;
real m_dot;
real pp;

pri_th = THREAD_SUB_THREAD(mix_th, 0);
sec_th = THREAD_SUB_THREAD(mix_th, 1);


if(C_T(cell, mix_th)>=T_SAT)
{

m_dot= -2*C1/(2-C1)*sqrt(MW/2/PI/RR)*(C_R(cell, pri_th)*LAT_HT*fabs(T_SAT-C_T(cell,sec_th)))/pow(T_SAT,1.5)*abs(C_VOF_G(cell, pri_th));

dS[eqn] = -2*C1/(2-C1)*sqrt(MW/2/PI/RR)*C_R(cell, pri_th)*LAT_HT/pow(T_SAT,1.5)*abs(C_VOF_G(cell, pri_th));

}
else
{
m_dot = 2*C1/(2-C1)*sqrt(MW/2/PI/RR)*(C_R(cell, pri_th)*LAT_HT*fabs(T_SAT-C_T(cell,mix_th)))/pow(T_SAT,1.5)*abs(C_VOF_G(cell, pri_th));
dS[eqn] =-2*C1/(2-C1)*sqrt(MW/2/PI/RR)*C_R(cell, pri_th)*LAT_HT/pow(T_SAT,1.5);
}
return LAT_HT*m_dot;
}

[AlexanderZ]

most likely you have division by zero somewhere in your code

also C_VOF_G is a vector, it has C_VOF_G[0], C_VOF_G[1], C_VOF_G[2] components
to get ist's magnitude you wanna use NV_MAG(C_VOF_G()) macro

[hitzhwan]

Originally Posted by AlexanderZ

most likely you have division by zero somewhere in your code

also C_VOF_G is a vector, it has C_VOF_G[0], C_VOF_G[1], C_VOF_G[2] components
to get ist's magnitude you wanna use NV_MAG(C_VOF_G()) macro

Hi，Alexander， thank you so much for your help. You mean I should use
NV_MAG(C_VOF_G(c,0)) to replace C_VOF_G(cell, pri_th)，and use
NV_MAG(C_VOF_G(c,1)) to replace C_VOF_G(cell, sec_th).Is that right? Thank you so much for you help. Hope you have a good weekday.

[AlexanderZ]

yes, I think so. But you should test it