How to set drainage boundary conditions

[PEI0214]

Hi，
In porous fluids, I see that simply setting porepressure=0 in the BCs allows for drainage.
So how to set the boundary conditions to achieve first drainage, then no drainage? Is how to set the control drain switch？

Thanks for your help.

[cpgr]

You can use the [Controls] system to turn BC's on/off according to some criteria.

[PEI0214]

Thank you very much for your answer. I think I know what to do.