hypersonic HLLC/AUSM 2nd order

melrose · January 30, 2013, 21:23

Hi,
I have been having a play with SU2 over the past couple of days. I took the euler wedge example (inv_edge.cfg) and ramped the freestream conditions to Mach 8 at 27km altitude (P=1847Pa, T=233K, U=2398m/s). With a small tweak to the CFL ramping the JST method works excellently, but I'm not having much success with the HLLC and AUSM 2nd order schemes. The best I've managed is 3 orders of magnitude residual drop, which is pretty poor compared to the near machine accuracy of the JST (and 1st order AUSM/HLLC).

If it's not too much trouble, could someone with more experience with the code run this case with the HLLC and AUSM 2nd order schemes and let me know whether it's just my incompetence that is preventing me from getting convergence please

.

Best,
Melrose

copeland · January 31, 2013, 01:22

Hey Melrose,

The upwinding schemes at hypersonic Mach numbers can be strongly influenced by the settings used for the flux limiter. Which limiter are you using and what are the limiter parameters you've assigned? Also, the limiters tend to work best when the solver is non-dimensionalized such that the conserved quantities are order 1, so if you haven't done that yet, I would suggest playing with the reference/non-dimensionalization settings, then try adjusting the limiter parameters.

It's a bit of an art, sometimes. Please share with the community if you find settings that work well!

Regards,
Sean

January 30, 2013, 21:23	hypersonic HLLC/AUSM 2nd order	#1
melrose New Member Melrose Join Date: Nov 2012 Posts: 1 Rep Power: 0	Hi, I have been having a play with SU2 over the past couple of days. I took the euler wedge example (inv_edge.cfg) and ramped the freestream conditions to Mach 8 at 27km altitude (P=1847Pa, T=233K, U=2398m/s). With a small tweak to the CFL ramping the JST method works excellently, but I'm not having much success with the HLLC and AUSM 2nd order schemes. The best I've managed is 3 orders of magnitude residual drop, which is pretty poor compared to the near machine accuracy of the JST (and 1st order AUSM/HLLC). If it's not too much trouble, could someone with more experience with the code run this case with the HLLC and AUSM 2nd order schemes and let me know whether it's just my incompetence that is preventing me from getting convergence please . Best, Melrose

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January 31, 2013, 01:22		#2
copeland Member Sean R. Copeland Join Date: Jan 2013 Posts: 40 Rep Power: 13	Hey Melrose, The upwinding schemes at hypersonic Mach numbers can be strongly influenced by the settings used for the flux limiter. Which limiter are you using and what are the limiter parameters you've assigned? Also, the limiters tend to work best when the solver is non-dimensionalized such that the conserved quantities are order 1, so if you haven't done that yet, I would suggest playing with the reference/non-dimensionalization settings, then try adjusting the limiter parameters. It's a bit of an art, sometimes. Please share with the community if you find settings that work well! Regards, Sean