Zero gradient BC for outlet
 

Hello,

I am modeling a 2D supersonic flow over a cylinder, and only 3 boundary conditions are involved: supersonic inlet, outlet and wall.

I was wondering if there is an outlet BC type that allows zero gradient, or zero flux, which I can find in SU2.

Many thanks,
Paul

Sorry. I guess I found the answer "For this test case, the inlet marker will be set to a MARKER_SUPERSONIC_INLET boundary condition, while the outlet marker will be set to the MARKER_OUTLET condition. In supersonic flow, all characteristics point into the domain at the entrance (inlet marker), so all flow quantities can be specified (no information travels upstream). At the exit, however, all characteristics are outgoing, meaning that no information about the exit conditions is required. Therefore, the outlet marker is set to the outlet boundary condition which, in supersonic flow, simply extrapolates the flow variables from the interior domain to the exit. In practice, a low back pressure is supplied to the MARKER_OUTLET boundary condition in the configuration file, but the propagation of information in this supersonic flow make it unnecessary information."