Velocity Pressure Coupling

Chris Lucas · November 2, 2010, 04:35

Hi,

I have a question regarding the pressure velocity coupling in OpenFoam. When I look at the literature, the velocity is first predicted by the equation u*=(1/A_p)*(H(u*)-grad(p_old)). Then the velocity is corrected by using the simple or piso algorithm.

However, when I look at the source code of e.g. rhoSimpleFoam, the velocity prediction is done by u*=(1/a_p)*H(u*). Why is the part of the equation containing the old pressure missing in OpenFoam?

Regards,
Christian

chegdan · November 2, 2010, 17:14

rhoSimpleFoam is a compressible solver, so I'm not familiar with it. Take a look at simpleFoam for the simple algorithm and icoFoam for the PISO algorithm. also, here is a quick explanation of the PISO algorithm in icoFoam.

http://www.tfd.chalmers.se/~hani/kur...pplication.pdf

Hope this helps

Dan

November 2, 2010, 04:35	Velocity Pressure Coupling	#1
Chris Lucas Senior Member Christian Lucas Join Date: Aug 2009 Location: Braunschweig, Germany Posts: 202 Rep Power: 18	Hi, I have a question regarding the pressure velocity coupling in OpenFoam. When I look at the literature, the velocity is first predicted by the equation u=(1/A_p)(H(u)-grad(p_old)). Then the velocity is corrected by using the simple or piso algorithm. However, when I look at the source code of e.g. rhoSimpleFoam, the velocity prediction is done by u=(1/a_p)H(u). Why is the part of the equation containing the old pressure missing in OpenFoam? Regards, Christian

November 2, 2010, 17:14	rhoSimpleFoam is a compressible solver	#2
chegdan Senior Member Daniel P. Combest Join Date: Mar 2009 Location: St. Louis, USA Posts: 621 Rep Power: 0	rhoSimpleFoam is a compressible solver, so I'm not familiar with it. Take a look at simpleFoam for the simple algorithm and icoFoam for the PISO algorithm. also, here is a quick explanation of the PISO algorithm in icoFoam. http://www.tfd.chalmers.se/~hani/kur...pplication.pdf Hope this helps Dan

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