change boundary condition on the fly
 

It there a way to change the BC type during simulation?

I have a cavity whose top is a symmetry plane except a small patch where some fluids will be injected for 5 s. After the injection (the injecting needle will be removed), I want that small patch to be symmetry patch also.

How do I code this? Or is there a way to do it?

Right now, I have to run two simulations (with and without the injection patch) and then map the solutions.