Force Mach number = 1 as boundary condition
 

Hello everyone!

I am using my own Matlab&C++ code to simulate a compressible reactive flow through a duct. It's modelled by reactive Euler equations in conservative form (solved by Riemann solvers), boundaries are coped with using ghost cells. I have a 1D and a 2/3D version of the code and need to use both.
As an outlet condition I now need the Mach number to be equal to 1 because the fluid flows into a turbine which I won't simulate. I have seen a way to set the Mach number for subsonic conditions but M=1 seems to be considered supersonic. The fluid in the duct may be sub- or supersonic. As I have no idea how to deal with this condition I'll be grateful for any idea and help.

I hope that's all the information needed to suggest a solution and thank you in advance!