Riemann solvers Q2

shuo · October 26, 2009, 22:24

Hi all,

I have coded a HLLC WAF (weighted aberaged flux) Riemann solver to simulate a supersonic impinging jet issued from a DC-D nozzle. The Euler equations are solved with slip wall B.C. It is appropriate to use Riemann solver to extract acoustic information from the flow? And is it ok to introduce instability at the nozzle exit to extract turbulent fluctuations?

Regards

Shuo

Killercam · November 27, 2009, 11:45

Shuo,

Riemann solvers are typically used in conjunction with a Godunov scheme, and thats what your HLLC scheme is based around. This is used for non-dissapative regimes where the equations can be recast as a hyperbolic system of PDEs, or a system of conservation laws. The Riemann solver can extract nothing, it is used to obtain the intercell numerical fluxes at the cell boundaries - thats it (which is complicated in its own right). I am not sure if I understand you question, but these Godunov scheme are mainly used to resolve wave propagation, and can indeed resolve the sound/pressure/contact waves in such Newtonian flows - if this is you question the answer is yes.

See any papers on Godunov solvers for tests you can undertake to understand the effect of wave propagations in such flows.

Hope this has helped.

Dr. Killercam

October 26, 2009, 22:24	Riemann solvers Q2	#1
shuo New Member shuo Join Date: Apr 2009 Posts: 17 Rep Power: 17	Hi all, I have coded a HLLC WAF (weighted aberaged flux) Riemann solver to simulate a supersonic impinging jet issued from a DC-D nozzle. The Euler equations are solved with slip wall B.C. It is appropriate to use Riemann solver to extract acoustic information from the flow? And is it ok to introduce instability at the nozzle exit to extract turbulent fluctuations? Regards Shuo

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November 27, 2009, 11:45		#2
Killercam New Member Nicholas F Camus Join Date: Sep 2009 Location: London, England. Posts: 21 Rep Power: 17	Shuo, Riemann solvers are typically used in conjunction with a Godunov scheme, and thats what your HLLC scheme is based around. This is used for non-dissapative regimes where the equations can be recast as a hyperbolic system of PDEs, or a system of conservation laws. The Riemann solver can extract nothing, it is used to obtain the intercell numerical fluxes at the cell boundaries - thats it (which is complicated in its own right). I am not sure if I understand you question, but these Godunov scheme are mainly used to resolve wave propagation, and can indeed resolve the sound/pressure/contact waves in such Newtonian flows - if this is you question the answer is yes. See any papers on Godunov solvers for tests you can undertake to understand the effect of wave propagations in such flows. Hope this has helped. Dr. Killercam