Disturbance in the transonic region using the PR_GAS fluid model

[antoine-metsue]

Hello !

I have been trying to run the NICFD nozzle case of the tutorials with CO2 instead of MDM, using the Peng-Robinson equation of state. However, I get some disturbance near the wall, that eventually cause the simulation to crash. I have run a few tests and this is what I was able to deduce:

-The disturbance occurs when the flow is transonic/supersonic, not if the flow stays subsonic.
-The disturbance does not appear when an Euler wall condition is imposed, but it appears when a heat-flux (no slip) condition is imposed.
-It does not appear when using the ideal gas model.
-It will appear either with a non structured mesh or a structured one.
-It appears even if y+ < 1
-It will occur even at low CFL numbers (smaller than 1) when using the Euler implicit scheme.
-It does not seem to occur when using the Euler explicit scheme, though I still have to make tests to be 100% sure.

simulation_files.zip