[Anshs]

I'm trying to compute the interfacial area between 2 phases, given that there are 3 phases. I have tried a UDF here. The three phases are water, oil, air. Computing the area between air (phase 2) and water (phase 0) only.

Screenshot 2020-06-07 at 6.07.27 AM.jpg

I had constructed a code for 2 phase flows, but now I want to implement in 3 phases:

2 phase code:

#include "udf.h"

DEFINE_ADJUST(store_gradient, domain)

{

Thread *t;
Thread **pt;
cell_t c;


double A_inter3;


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_NULL);
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];


C_UDMI(c,t,0) = NV_MAG(C_VOF_G(c,ppt)) ;

A_inter3 += C_UDMI(c, t, 0)*C_VOLUME(c, ppt) ;


Free_Storage_Vars(pDomain,SV_VOF_RG,SV_VOF_G,SV_NULL);

}

}

3 phase code: ( in code ppti = water , and pptj = air )

#include "udf.h"

DEFINE_ADJUST(store_gradient, domain)

{

Thread *t;
Thread **pt;
cell_t c;


double A_inter3;


int pdi = 0.;
int pdf = 2.;

Domain *pDomaini = DOMAIN_SUB_DOMAIN(domain,pdi);

{
Alloc_Storage_Vars(pDomaini,SV_VOF_RG,SV_VOF_G,SV_NULL);
Scalar_Reconstruction(pDomaini, SV_VOF,-1,SV_VOF_RG,NULL);
Scalar_Derivatives(pDomaini,SV_VOF,-1,SV_VOF_G,SV_VOF_RG,
Vof_Deriv_Accumulate);
}

Domain *pDomainj = DOMAIN_SUB_DOMAIN(domain,pdj);

{
Alloc_Storage_Vars(pDomainj,SV_VOF_RG,SV_VOF_G,SV_NULL);
Scalar_Reconstruction(pDomainj, SV_VOF,-1,SV_VOF_RG,NULL);
Scalar_Derivatives(pDomainj,SV_VOF,-1,SV_VOF_G,SV_VOF_RG,
Vof_Deriv_Accumulate);
}


mp_thread_loop_c (t,domain,pt)

Thread *ppti = pt[pdi];
Thread *pptj = pt[pdi];

if ( ( C_VOF(c,ppti)*C_VOF(c,pptj) > 0.21 ) && (C_VOF(c,ppti) + C_VOF(c,pptj) >0.95) )
{


C_UDMI(c,t,0) = NV_MAG(C_VOF_G(c,ppti)) ;

A_inter3 += C_UDMI(c, t, 0)*C_VOLUME(c, ppti) ;



Free_Storage_Vars(pDomain,SV_VOF_RG,SV_VOF_G,SV_NULL);

}

}