Boundary Condition in PISO
 

Hello, I'm developing an incompressible flow code using 'PISO' algorithm but I cannot find appropriate boudary condition. Is there any special boundary condition for 'PISO' algorithm(Especially for pressure correction equation)? I implemented pressure correction equation to 2nd correction step, but in comparison with SIMPLE method, the 2nd correction was not effective so I see the 2nd correction step implementation has some problem with boundary condition. If you have any advice, thank you for your answer. Have a nice day.

Re: Boundary Condition in PISO
 

Boundary conditions are not easy to implement with PISO. For the pressure Poisson equation you can get a boundary condition (Neumann type) by writing the normal component of the momentum equation on the boundary (using of course the chosen boundary conditions for velocity). Then you must introduce an additional relation which allows you to get rid of the unknown term involving the velocity corrections in this equation. You can set this term equal to zero or extrapolate it from the interior nodes.