[lehoanganh07]

Hi everyone,

I am doing my numerical simulation of cavitating flow in rectangular Nozzle. I am having trouble with boundary condition.

Firstly, I use mixed Neumman and Drichlet boundary condition at inlet and outlet section. Inlet is subsonic flow so that I fixed total pressure, flow direction and void fraction. Outlet also assume that subsonic flow, so just static pressure fixed. But the solution divergent due to very strong pressure wave propagation.

I read in book that, for this situation, I need use non-reflective BC or Convective BC.

example, convective BC at oulet: d(phi)/dt + U d(phi)/dx = 0 with phi: velocity, pressure, density, mass fraction,...

But my question, if use CBC, how to fix the outlet pressure?
And which boundary is suitable for my case?