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AKHIL123 June 21, 2019 00:19

Fluent udf on mass transfer
 
hi,i am currently working on a project based on mass diffusion from o2 to water based on ficks law via solving transport equations.my udf is shown below,its compiling well,but during running its showing segmentation fault.

/* UDF to define Mass transfer */
#include "udf.h"
#include "para.h"
#include "math.h"
#include "stdio.h"
#include "prf.h"
#include "mem.h"
/********************************************/
/*USER INPUTS*/
double C_sat=8e-3,D=62.24e-8,maxmesh=3.2e-4;
/******************************************/
/*GLOBAL VARIABLES THROUGH UDF*/
/*calculation of discretization length based on void fraction and normal*/
extern double GetVolumenSchwerpunkt(double Volumen,double Normale[3]);
/************************************************** *********/
/*Determination of dispersed phase area*/

DEFINE_ADJUST(store_gradient, domain)
{
Thread *t;
Thread **pt;
cell_t c;
int phase_domain_index = 0.;
Domain *pDomain = DOMAIN_SUB_DOMAIN(domain,phase_domain_index);
{
Alloc_Storage_Vars(pDomain,SV_VOF_RG,SV_VOF_G,SV_N ULL);
Scalar_Reconstruction(pDomain, SV_VOF,-1,SV_VOF_RG,NULL);
Scalar_Derivatives(pDomain,SV_VOF,-1,SV_VOF_G,SV_VOF_RG,
Vof_Deriv_Accumulate);
}


mp_thread_loop_c (t,domain,pt)
if (FLUID_THREAD_P(t))
{
Thread *ppt = pt[phase_domain_index];
begin_c_loop(c,t)
{
C_UDMI(c,t,0)=NV_MAG(C_VOF_G(c,ppt));
C_UDMI(c,t,1)=C_VOF_G(c,ppt)[0];
C_UDMI(c,t,2)=C_VOF_G(c,ppt)[1];

}
end_c_loop (c,t)
}
Free_Storage_Vars(pDomain,SV_VOF_RG,SV_VOF_G,SV_NU LL);

}
/************************************************** *******************/
\
/*Calculation of dispersed concentration in continuous phase*/
DEFINE_ADJUST(max_C_liq,domain)
{
Thread *t;
Thread **pt;
cell_t c;
real C_liq,C_liq_pt;
real m_f,m_f_c,m_f_t,m_f_t_C;
int phase_domain_index=1.;/*1 mixture*/
Domain *pDomain=DOMAIN_SUB_DOMAIN(domain,phase_domain_ind ex);
mp_thread_loop_c(t,domain,pt)
if (FLUID_THREAD_P(t))
{
Thread *ppt=pt[phase_domain_index];
begin_c_loop(c,t)
{

/*m_f=species mass fraction of dispersed phase at actual time*/
m_f=C_YI(c,ppt,0);
C_UDMI(c,t,3)=m_f; if (C_VOF(c,ppt) !=0)
m_f=C_YI(c,ppt,0);
else
m_f=0;
C_UDMI(c,t,4)=m_f*1205/18; /*concentration kg/m3*/
m_f_c=m_f*1205/18; /*concentration kg/m3*/
C_UDMI(c,t,5)=m_f_c; /*concentration kg/m3*/
if (m_f_c>=C_sat)
m_f_c=C_sat;
else
m_f_c=m_f_c;
C_UDMI(c,t,6)=m_f_c;/*concentration kg/m3*/
if (C_VOF(c,ppt) !=0)
C_liq=m_f_c;/*C_liq is the concentration of o2 in the liquid phase at actual time*/
else
C_liq=0;
C_UDMI(c,t,7)=C_liq; /*C_liq kg/m3 the value of c in liquid at t*/
C_UDMI(c,t,8)=C_liq/18;/*C_liq kmol/m3 the value of c in liquid at t*/
}
end_c_loop (c,t)
}

}
/************************************************** *********/
/*Mass transfer from dispersed phase to continuous phase*/
DEFINE_MASS_TRANSFER(mstr_d_erg,cell,thread,from_i ndex,from_species_index,to_index,to_species_index)
{
cell_t c;
Thread *t;
Thread *gas=THREAD_SUB_THREAD(t,from_index);
Thread *liq=THREAD_SUB_THREAD(t,to_index);
double m_lq=0.0;
double volume_liquid=0.;
double Nx;
double Ny;
double Erg=0.0;
double Erg1=0.0;
double Normale[3];
double Volumen;

volume_liquid=C_VOLUME(c,t)*C_VOF(cell,liq);
C_UDMI(c,t,9)=volume_liquid;
Nx=C_UDMI(c,t,1);
Ny=C_UDMI(c,t,2);
Normale[0]=Nx;
Normale[1]=Ny;
Volumen=C_VOF(cell,liq);
C_UDMI(c,t,10)=Volumen;
if (C_VOF(c,liq) !=0)
{
Erg=fabs(maxmesh*((1-C_UDMI(c,t,10)/2)));
}
else
Erg=0.0;
C_UDMI(c,t,11)=Erg;
if (C_VOF(c,liq)>0.05&&Erg>(maxmesh*1e-3)&&C_sat>C_UDMI(c,t,8))
m_lq=C_UDMI(c,t,0)*(D/Erg)*(C_sat-C_UDMI(c,t,8));
else
m_lq=0;
C_UDMI(c,t,12)=m_lq;
return m_lq;
}


could anyone help me to find the error.

AKHIL123 June 24, 2019 04:45

yes ,i want to simulate mass transfer from gas to liquid

Smai February 14, 2021 10:54

Have you found Solution
 
Can you put comments in this udf, so its easy for newbies to understand this udf . Thanks Hope for soon reply

snr1 May 4, 2022 12:34

Hello akhil, did you able to solve the issue?


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