Recently I am dealing with a 2 stages compressor. I want to vary the outlet static pressure (writeen as Ps) according to the timesteps (writeen as t). And I am going to use a function such as:

Ps=P1&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp(t<<O>t1);

Ps=0.01*t&nbsp&nbsp(t1<<O>t<<O>t2);

Ps=P2&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp&nbsp(t><O>t2);

The P1,P2,t1 and t2 are specified. So, could someone tell me that how to define the boundary condition in such a problem, should I use Fortran?

You can create a function in CFX-Pre which can be timestep dependend, like pressure(ctstep). Then don´t describe your boundary with a pressure value but with this function as an expression.

Thank you Adam!