Where is the solve of UEqn in twoPhaseEulerFoam?

Qingang Xiong · July 5, 2012, 09:51

Hi Foamers,
In the manual "Derivation, Modelling and Solution of the Conditionally Averaged Two-Phase Flow Equations" by Weller et al. they said that momentum equations are constructed and solved. But in the solver code of twoPhaseEulerFoam, I just see UaEqn.relax(), not solve(). So could anyone explain to me how about this issue? Thank you!

bruce · July 8, 2012, 10:51

I think the momentum equation is not predicted and is only corrected in pressure loop which is conservative. (see pEqn.H)

alberto · July 9, 2012, 02:13

The momentum equation is defined (excluding some terms, which are transferred to the pressure equation), and the velocity is predicted with a single Jacobi step.

You could predict the velocity with a direct solution, including the transferred term by means of the reconstruct operator, however this might slow convergence down.

masimasiqi · June 3, 2019, 09:00

Quote:

Originally Posted by alberto

The momentum equation is defined (excluding some terms, which are transferred to the pressure equation), and the velocity is predicted with a single Jacobi step.

You could predict the velocity with a direct solution, including the transferred term by means of the reconstruct operator, however this might slow convergence down.

could you please explain how to use a reconstruct operator?

I am using twoPhaseEulerFoam(5.0) and have read some literatures about the solving process. As you said, the solver only predict the velocity rather than solve it... how could I get the value of velocity?

thanks! It would be a lot of help.

July 5, 2012, 09:51	Where is the solve of UEqn in twoPhaseEulerFoam?	#1
Qingang Xiong New Member Qingang Xiong Join Date: May 2012 Location: Ames, IA, USA Posts: 20 Rep Power: 13	Hi Foamers, In the manual "Derivation, Modelling and Solution of the Conditionally Averaged Two-Phase Flow Equations" by Weller et al. they said that momentum equations are constructed and solved. But in the solver code of twoPhaseEulerFoam, I just see UaEqn.relax(), not solve(). So could anyone explain to me how about this issue? Thank you!

July 9, 2012, 02:13		#3
alberto Senior Member Alberto Passalacqua Join Date: Mar 2009 Location: Ames, Iowa, United States Posts: 1,912 Rep Power: 36	The momentum equation is defined (excluding some terms, which are transferred to the pressure equation), and the velocity is predicted with a single Jacobi step. You could predict the velocity with a direct solution, including the transferred term by means of the reconstruct operator, however this might slow convergence down. __________________ Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats (current status: http://albertopassalacqua.com/?p=1541) OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using.

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July 8, 2012, 10:51		#2
bruce Member bruce Join Date: May 2009 Location: Germany Posts: 42 Rep Power: 16	I think the momentum equation is not predicted and is only corrected in pressure loop which is conservative. (see pEqn.H)