How high of a Mach number / flight regime can PyFR handle?

Cases
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How high of a Mach number can PyFR stay stable with? With using entropy filtering, I know PyFR can handle shocks, but I am wondering once you get closer to Mach 2-4 (not hypersonic), if PyFR is unstable?

Also, kind of a related question, but I could not find any good information on this in the documentation. But when defining my initial and boundary conditions, how do I scale all variables so my initial velocity = 1? PyFR seems to prefer that. When I enter everything in metric units, I get instability. For example, say I am trying to recreate flow over an airfoil with chord length = 2 meters, and initial u = 200 m/s and pressure and density is sea-level 101325 pa and 1.225 kg/m^3. How would I define my initial/boundary conditions such that u = 1, p = some number, rho = some number?

I greatly appreciate your help.

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I’ve had students run cases up to Mach 10. In this paper Positivity-preserving entropy-based adaptive filtering for discontinuous spectral element methods - ScienceDirect Tarik runs a Mach 800 jet case.

PyFR doesn’t per se prefer, or indeed presuppose, any particular unit system. You can use whatever system of units you like. So you can indeed do everything in SI units if you wish.

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