boundary condition

[Sushmitharao46]

For swbli case, the boundary condition specified at outlet is non reflecting boundary condition but which non reflecting boundary condition is specified is not mentioned anywhere, Can you please give information on which kind of non reflecting bc is implemented at outlet?

[davidem88]

At the outlet, we use a standard non-reflecting boundary condition based on a characteristic decomposition at the boundary, where waves entering the domain are suppressed. You can find the procedure in the paper by Pirozzoli and Colonius Generalized characteristic relaxation boundary conditions for unsteady compressible flow simulations JCP 2013. For a supersonic outlet, we do not use relaxation.