[JinYuKai]

Hey all,
Recently I want to use Fluent's user define scalars(uds) to solve the nucleation of equiax grain in a ingot cast problem with Fluent Eulerian Mutiphase Model. The control equation for the nucleation of equiaxed grain as follow:

It is my first time to ask my question here.I am sorry I donot know why my Browser cannot insert images here.I can just provide a paper here,whoes title is"Modeling of Globular Equiaxed Solidification with a Two-Phase Approach".


My code is shown:
DEFINE_UDS_UNSTEADY(uds_unsteady_mixture,c,t,i,apu ,su)
{
Thread *t_liq, *t_col;
t_liq=THREAD_SUB_THREAD(t, 0);
t_col=THREAD_SUB_THREAD(t, 1);

real dt;
real phi_old;
real volume;
real rho=1.0;

dt=CURRENT_TIMESTEP;
phi_old=C_UDSI_M1(c,t,i);
volume=C_VOLUME(c,t);
*apu=-rho*volume/dt;
*su=rho*volume*phi_old/dt;

}
DEFINE_UDS_FLUX(uds_flux_mixture,f,t,i)
{
Thread *t_liq, *t_col;
t_liq=THREAD_SUB_THREAD(t, 0);
t_col=THREAD_SUB_THREAD(t, 1);

real NV_VEC(psi);
real NV_VEC(A);
NV_D(psi,=,F_U(f,t_col),F_V(f,t_col),F_W(f,t_col)) ;
NV_S(psi,*=,1.0);
F_AREA(A,f,t);
return NV_DOT(psi,A);
}
DEFINE_SOURCE(uds_source_mixture,c,t,dS,eqn)
{
Thread *t_liq, *t_col;
t_liq=THREAD_SUB_THREAD(t, 0);
t_col=THREAD_SUB_THREAD(t, 1);

real delt_T,n_max=5e+12,delt_Tsigma=1.0,delt_TN=5.0;
real Tf=1808.15;
real dn_ddelt_T;
real delt_max;
real N,N0;

N0=1e+09;
delt_T=Tf+SLOPEM*C_YI(c,t_liq,0)-C_T(c,t);
if(delt_T>=delt_max)
{
delt_T=delt_max;
}
C_UDMI(c,t,13)=delt_T;

dn_ddelt_T=n_max*exp(-0.5*pow((delt_T-delt_TN)/delt_Tsigma,2.0));
N=dn_ddelt_T*delt_T/CURRENT_TIMESTEP;
if(delt_T<=0.0)
{
N=0.0;

}
else
{
N=N;
}
dS[eqn]=0.0;
return N;
}

I know little about the details ,espesially the source term and convection term.Anyone who can help me implement this UDS?Thanks
In addition,how can i use the scaler value in another program if i successfully run the code？

[JinYuKai]

Anyone who can help me or give me some reference?I am waiting for your reply.