Simple upwinding for the hyperbolic points in the TSD equation( Transonic small disturbance) leads to a first order accurate scheme in the supersonic region. Can anybody help me with making this scheme second order accurate for the aforementioned region. Thanks a lot.

Hi, I'm also working on TSD equation. I think you need a type-dependent mixed difference scheme so I send you via separate E-Mail the second-order Engquist-Osher scheme for the streamwise term of TSDE. This scheme is central in the subsonic region and backward (upwind) in supersonic region. I'd like to know if you are working on Unsteady TSDE or if you have any general test cases.