Reply To: use of temperature and mass fraction gradients in UDF

[Ramesh Chandra Mishra]

Hi

i am solving an equation which requires concentration gradient as a term. So i write concentration as mass fraction*density to a C_UDSI and then use C_UDSI_G to solve the equation. But I am getting zero everytime. Please note that i don't disable solving the equation for UDS. Is it because of that or there is something to be done in my case file?

A snippet of code is as follows:

thread_loop_f(t, d)

{

    begin_f_loop(f,t)

    {

        F_CENTROID(x, f, t);

if (x[0] >= 108  && x[0] <=  126 &&  x[1] == 18 && x[2] >= 90  && x[2] <= 126 )

{

                    F_AREA(A,f,t);

co = F_C0(f, t);              

to = THREAD_T0(t);      //obtaining corresponding thread of adjacent cell

real integrand;

real conc_grad_roof;

real mu_t_roof = C_MU_T(co,to);        //turbulent viscosity 

C_UDSI(co,to,0)= C_YI(co,to,0) * RHO_1;   //storing concentration of CO as user defined scalar(UDS)

conc_grad_roof=(C_UDSI_G(co,to,0)[1]);       //concentration gradient of CO

 

integrand = (mu_t_roof /0.7)*conc_grad_roof;     //TURBULENT POLLUTANT FLUX

PCH_turb_roof -= integrand*NV_MAG(A);            //Overall value of PCH integral

                }

            }

                          

        end_f_loop(f,t)

}