Coefficient psi in Gamma Differencing scheme

Gunnern · March 26, 2016, 15:39

Dear foamers,

I am currently setting up a transient incompressible CFD simulation and want to use the Gamma differencing scheme for convection discretization of bounded scalars.

Therefore I am wondering if there is any relation between the coefficient ψ that needs to be specified and the βm coefficient from professor Jasak's PhD thesis. The User Guide states that ψ needs to be specified between 0 ≤ ψ ≤ 1, where lower values giver better accuracy and higher values give better convergence. Similarly, βm needs to be specified as 0.1 ≤ βm ≤ 0.5, where lower values also give better accuracy and higher values better convergence. Prof. Jasak states that βm is a constant used by most NVD schemes.

That leads me to the following conclusion: βm is the same as ψ, but for the Gamma scheme it is recommended to keep this constant between 0.1 and 0.5, not between 0 and 1 as for other TVD/NVD schemes.

Does anyone know if this is correct?

Best regards,
G

s.v · June 6, 2021, 16:29

I think post # 8 on this thread Interpolation in OpenFoam addresses this question ....

Cheers ....

March 26, 2016, 15:39	Coefficient psi in Gamma Differencing scheme	#1
Gunnern New Member Join Date: Nov 2015 Posts: 3 Rep Power: 10	Dear foamers, I am currently setting up a transient incompressible CFD simulation and want to use the Gamma differencing scheme for convection discretization of bounded scalars. Therefore I am wondering if there is any relation between the coefficient ψ that needs to be specified and the βm coefficient from professor Jasak's PhD thesis. The User Guide states that ψ needs to be specified between 0 ≤ ψ ≤ 1, where lower values giver better accuracy and higher values give better convergence. Similarly, βm needs to be specified as 0.1 ≤ βm ≤ 0.5, where lower values also give better accuracy and higher values better convergence. Prof. Jasak states that βm is a constant used by most NVD schemes. That leads me to the following conclusion: βm is the same as ψ, but for the Gamma scheme it is recommended to keep this constant between 0.1 and 0.5, not between 0 and 1 as for other TVD/NVD schemes. Does anyone know if this is correct? Best regards, G

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Limiter in gamma scheme	bamaoli	OpenFOAM Running, Solving & CFD	0	October 7, 2015 16:48
Differencing Scheme for Advection Problem	Simon Smokes	Main CFD Forum	2	April 8, 2015 10:59
Why RNGkepsilon model gives floating error	shipman	OpenFOAM Running, Solving & CFD	3	September 7, 2013 08:00
?to implement gamma differencing scheme	Gonski	Main CFD Forum	15	January 28, 2007 17:00
Differencing scheme for k-eps model	Ron Barer	Main CFD Forum	14	November 2, 2000 00:02

June 6, 2021, 16:29		#2
s.v New Member s.v Join Date: Jun 2021 Posts: 13 Rep Power: 4	I think post # 8 on this thread Interpolation in OpenFoam addresses this question .... Cheers ....