Acoustic waves in pressure based solver

michujo · October 18, 2013, 19:43

Hi people.

I had a discussion recently with a colleague regarding whether a pressure based solver would be capable of capturing acoustic waves.

If the fluid is incompressible it is obvious that the sound velocity is infinite and the pressure variations are felt immediately everywhere but, what if we introduce a dependency of the local density with pressure? Something like $\rho=\rho_{ref}\cdot(T-T_{ref})\cdot(P-P_{ref})$ . Would be observe pressure and density perturbations travelling at the sound speed in the simulations?

I hope you can give me an explanation or a reference that I can look into.

Thank you,
Michujo.

FMDenaro · October 19, 2013, 04:52

Quote:

Originally Posted by michujo

Hi people.

I had a discussion recently with a colleague regarding whether a pressure based solver would be capable of capturing acoustic waves.

If the fluid is incompressible it is obvious that the sound velocity is infinite and the pressure variations are felt immediately everywhere but, what if we introduce a dependency of the local density with pressure? Something like $\rho=\rho_{ref}\cdot(T-T_{ref})\cdot(P-P_{ref})$ . Would be observe pressure and density perturbations travelling at the sound speed in the simulations?

I hope you can give me an explanation or a reference that I can look into.

Thank you,
Michujo.

Hi, I don't understand the way in which you would insert the relation in the equations....furthermore, the relation has no sense in dimensional unit (p=rho*R*T is the thermodinamic relation).
You should give more details...

In any case, until you solve an elliptic equation for pressure, you can not have a time evolution for pressure waves.

October 18, 2013, 19:43	Acoustic waves in pressure based solver	#1
michujo Senior Member Join Date: Dec 2011 Location: Madrid, Spain Posts: 134 Rep Power: 16	Hi people. I had a discussion recently with a colleague regarding whether a pressure based solver would be capable of capturing acoustic waves. If the fluid is incompressible it is obvious that the sound velocity is infinite and the pressure variations are felt immediately everywhere but, what if we introduce a dependency of the local density with pressure? Something like $\rho=\rho_{ref}\cdot(T-T_{ref})\cdot(P-P_{ref})$ . Would be observe pressure and density perturbations travelling at the sound speed in the simulations? I hope you can give me an explanation or a reference that I can look into. Thank you, Michujo.

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