Hi, I need to find the difference in pressure of gas and liquid phase flow in my packed bed. I have used the macro C_P(cell,thread) with the liquid and gas phase threads, but Fluent gives the same value for both. Is there a way to access separate phase pressures? A part of my UDF is given below. Please help.

C_UDMI(c,t,0) = C_P(c,tp_g); /* Gas phase pressure */ C_UDMI(c,t,1) = C_P(c,tp_l); /* Liquid phase pressure */ C_UDMI(c,t,2) = C_P(c,tp_l)-C_P(c,tp_g); /* This returns zero */

PS: I have looked at the phase pressures (dynamic) contours, it is different for both the phases.

In multiphase flows Fluent uses a common pressure ... discussed in manual.