What kind of boundary conditions should I use for the walls and outlets of the shocktube case in sonicFoam, rhoSonicFoam...? It keeps giving me singularity errors when I use extrapolatedOutlet for the two exits and wall for the four walls.
Shuo

[smith]

Dpends on your application. If you want to model a closed shocktube then use reflective BC's, and expect reflected shocks, otherwise use open BC's, say with continuous velocity and pressure.

I don't know why extrapolaedOutlet wouldn't work, you'd have to ask the OpenCFD people about that.