modeling a pump-turbine runner
 

hi everybody
I have a project to simulate a pump turbine in both pump and turbine modes and then optimize it.
I've already simulated the turbine mode but now,modeling the pump mode and setting its boundary conditions made me some how puzzled!
I want to know, except that the inlet and outlet and the direction of the rotation change,which options should I chose for the runner walls and the fluid zone.what is difference between pump and turbine mode for these last two?
thanks