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 Zheng.Zhi August 26, 2012 00:24

the UEqn.H at interPhaseChangeFoam

fvVectorMatrix UEqn
(
fvm::ddt(rho, U)
+ fvm::div(rhoPhi, U)
- fvm::Sp(fvc::ddt(rho) + fvc::div(rhoPhi), U)
- fvm::laplacian(muEff, U)
);

but the UEqn.H at interFoam

fvVectorMatrix UEqn
(
fvm::ddt(rho, U)
+ fvm::div(rhoPhi, U)
- fvm::laplacian(muEff, U)
);

I don't understand why need - fvm::Sp(fvc::ddt(rho) + fvc::div(rhoPhi), U) at interPhaseChangeFoam , Could anybody please answer me ? thanks very much.

 nimasam August 26, 2012 12:17

fvm::Sp(fvc::ddt(rho) + fvc::div(rhoPhi), U)
this term would be zero mathematically because
fvc::ddt(rho) + fvc::div(rhoPhi)
is global continuity equation, and i guess it is added to consider
any numerical error in global continuity equation

 abe April 8, 2013 07:32

I am agree with Nimasam. It returns the continuity equation value. I have checked the results in two conditions with and without this term. Results are fairly the same. However, I should say that by using this term it seems that the convergence speed is much better.
PS: in the OF22, this term has been removed!

 abe April 8, 2013 07:34

Quote:
 Originally Posted by nimasam (Post 378752) fvm::Sp(fvc::ddt(rho) + fvc::div(rhoPhi), U) this term would be zero mathematically because fvc::ddt(rho) + fvc::div(rhoPhi) is global continuity equation, and i guess it is added to consider any numerical error in global continuity equation

Hi, have you been able to use interPhaseChange in OF21 or 22?
I can get results by previous versions (i.e. OF1.5). But by these new versions results are not good at all.

ABE

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