negative pressure: Wall boundary, Mach 3, Euler

DSS

Hi,

I tried to simulate a test case with an initial start of Mach 3 flow. One of the case is the forward step, and another is the Ron-Ho-Ni channel.

When I run my code, after a few iterations, it crashes because of negative pressure value (in the vicinity of wall). In some literatures, it was mentioned that I need to do some entropy correction at the corners/singularity at wall. But, I am just wondering if there is an alternate way to do that. My code is an unstructed WENO type code, with NRBCs as proposed by Lele. For now, I use HLL flux for interfaces.

I tried to lower down the CFL to 0.01... but, still not getting that right...

Can anyone let me know where could I have possibly erred, or missed out? Should I do the entropy correction? and if I should do that, how can I generalize the boundary condition? (Say a Mach 5 problem for Scramjet intake)

(My code works well till Mach 2)

Thanks in advance for your help.