[SerClaudio]

Hi everyone,
I am trying to simulate the flow around a hypersonic vehicle to compute its Cd and Cl. The domain is a cylinder, with pressure-far-field BC on the inlet and pressure-outlet on all the other faces of the cylinder. The vehicle is simply modelled as a wall (cut-out from the domain), with prismatic layers to model the Boundary Layer.

I am using the density-based solver with steady-state conditions, energy on and SST K-omega viscous model. The fluid is modelled with ideal gas for the density, constant Cp and Sutherland's law for viscosity.

The problem is that when I run the simulation for Mach 2-4 I obtain reasonable values for the Cd and the residuals decrease down to ok-ish values (unfortunately continuity does not seem to go below 1e-2, though the Cd does not vary any longer over a large number of iterations). However, when I change the Mach number to 5 or more for the inlet pressure-far-field BC, the residuals diverge within a few hundred iterations and lead to a floating point exception.

Are there any other changes I need to make to change the flow from supersonic to hypersonic? Are there any problems with my set-up, or is it just a problem due to the mesh?