DPM drag force UDF

hedonists

Hi, I am doing submicron particle trajectory calculation. I need to write a UDF for the drag foce with a variable slip correction factor (a function of local temperature and pressure.) Do you know how to obtain the pressure and temperature at the current particle position and current time step? I tried to use the following, but it does not seem to work. Why?

cell_t c = RP_CELL(&p->cCell); Thread *t = RP_THREAD(&p->cCell); real pressure=C_P(c,t); real temp=C_T(c,t);

Thanks in advance! hedonist