Learning Forum

Hello,

 

I am trying to simulate Selective Laser Melting process at the mesoscale using Ansys Fluent. When writing the source term, I need to multiply it by the magnitude of the volume fraction gradient at the interface. For this, I have written the UDF given below where I store the magnitude of the volume fraction gradient in a UDMI using DEFINE_ADJUST and then call it in the DEFINE_SOURCE macros and assign it to the variable vf_g. If I don't call the C_UDMI in the DEFINE_SOURCE term the simulation runs without any issue and I can also visualize the C_UDMI in the contour plots, however, when I call it in DEFINE_SOURCE to multiply it with the source term, fluent simply crashes. Any errors that can be seen here? I have had the same issue regardless of the thread C_UDMI(c,t,0) wherein both the mixture domain thread and the phase thread result in fluent crashing

 

#include

#include

#include

#include

//#include

#include

#include

#include

 

#define PI 3.1415926535

#define domain_ID 3

DEFINE_ADJUST(adjust_gradient, domain)

{

    Thread *t;

    cell_t c;

    face_t f;

    domain = Get_Domain(domain_ID);

    /* Fill UDS with the variable. */

    thread_loop_c (t,domain)

    {

        begin_c_loop (c,t)

        {

            C_UDSI(c,t,0) = C_VOF(c,t);

        }

        end_c_loop (c,t)

    }

    thread_loop_f (t,domain)

    {

        if (THREAD_STORAGE(t,SV_UDS_I(0))!=NULL)

        begin_f_loop (f,t)

        {

            F_UDSI(f,t,0) = F_VOF(f,t);

        }

        end_f_loop (f,t)

    }

    domain=Get_Domain(1);

    /* Fill the UDM with magnitude of gradient. */

    thread_loop_c (t,domain)

    {

        begin_c_loop (c,t)

        {

            C_UDMI(c,t,0) = NV_MAG(C_UDSI_G(c,t,0));

        }

        end_c_loop (c,t)

    }

}

 

 

DEFINE_SOURCE(surface_laser,c,t,dS,eqn)

{

 

real current_time=CURRENT_TIME;

Thread *tp;

//parameters

real r=35e-6; // 100 micron

real P=50.0; //Power

 

Domain *subdomain;

 

    int phase_domain_index;

real v_d=0.12; 

real source;

real eta=0.5;

 

//start pos

real xs=1.5e-5+current_time*v_d;

real ys=6e-5;

// cell paramters

real x[ND_ND];

real T;

real Q;

 

real Sb;

real x1;

real y1;

    real z1;

    real vf;

real I_z;

real H_s; //

real gamma; // liq fraction 

real h; // HT coef

real T_a;

real n_fact; // normalizing factor

real Cpg;

real Cpl;

real Cpm;

real Cps;

real Cp;  // avg cell specific heat

real rho; // avg cell density

real rhog; // density of argon gas

 

real rhos; // solid density

real rhol; // liquid density

real rhom; // mixture density

 

real vf_g; //magnitude of volume fraction gradient

 

 

real s=15e-6;

 

Sb=5.67e-8;

h=25;

T_a=298;

C_CENTROID(x,c,t);

 

 

 

x1=x[0];

y1=x[1];

    z1=x[2]-5e-5+1.25e-6;

    tp = THREAD_SUB_THREAD(t,1);

    vf=C_VOF(c,tp); // get cell volume fraction

    T = C_T(c,tp); // get cell temperature

    gamma = C_LIQF(c,tp);// cell liquid fraction

    

    //Get the volume fraction gradient magnitude

    vf_g=C_UDMI(c,tp,0);

    

    //calculate mixture specific heat

    Cpg=520.64;

    Cps=462.656+0.1338*T;

    Cpl=790;

    Cpm=Cpl*gamma+Cps*(1-gamma);

    Cp=Cpm*vf+Cpg*(1-vf);

    

 

    // calculate mixture density

    rhog=1.6228;

    rhos=8000.0-800.0/1385.0*(T-273);

    rhol=6900.0-900.0/1277.0*(T-1723);

    rhom=rhol*gamma+rhos*(1-gamma);

    rho = vf*rhom + rhog*(1-vf);

 

    // calculate stabilizing factor

    n_fact=(2*rho*Cp)/(rhom*Cpm + rhog*Cpg);

 

    Q=0.23*P/(PI*r*r) * exp(-2*(pow(x1-xs,2)+pow(y1-ys,2))/pow(r,2));

 

    

    

    source=0;

    dS[eqn]=0;

if(vf>0.05 && vf<1){

        source= (Q-h*(T-T_a)-Sb*0.5*(pow(T,4)-pow(T_a,4)))*n_fact*vf_g;

    dS[eqn]=(-h-Sb*2*pow(C_T(c,tp),3))*n_fact*vf_g;

}

return source;

 

}

[Konstantin]

 

 

this is a multiphase model so you need to be careful with memory access. You define UDM in DEFINE_ADJUST on the thread, but then try to access them on the subthread in DEFINE_SOURCE. Are you assigning DEFINE_SOURCE to the mixture or to phases?