|November 21, 2015, 15:50||
+ or - pEqn().flux()?
Join Date: Apr 2015
Posts: 10Rep Power: 3
Why for some cases pEqn().flux() are subtracted, as for example:
phi = phiHbyA - pEqn().flux()as in applications\solvers\incompressible\simpleFoam\pEq n.H,
while for other cases are added, as for example
phi = phiHbyA + pEqn().flux()as in applications\solvers\compressible\rhoSimpleFoam\pE qn.H?
Thanks in advance,
|November 21, 2015, 20:06||
Join Date: Mar 2009
Location: London, England
Posts: 1,784Rep Power: 22
If your pressure laplacian has a minus sign (-), then it's
phi = phiHbyA + pEqn().flux()
This is the case in compressible solvers.
For incompressible solvers, the pressure laplacian has a positive sign and it's
phi = phiHbyA - pEqn().flux()
Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk
|November 23, 2015, 01:00||
does the + or - depend on how the pEqn is declared?
Join Date: Dec 2014
Posts: 66Rep Power: 4
i wonder if the + or - operation depends on how the pEqn is declared.
i mean for the incompressible solver pimpleFoam, the pEqn is
fvScalarMatrix pEqn ( fvm::laplacian(rAUf, p) == fvc::div(phiHbyA) );
phi = phiHbyA - pEqn.flux();
fvScalarMatrix pEqn ( fvm::laplacian(rAUf, p) - fvc::div(phiHbyA) );
fvScalarMatrix pEqn ( - fvm::laplacian(rAUf, p) + fvc::div(phiHbyA) );
another question, for the shallowWaterFoam, the "pEqn" is
fvScalarMatrix hEqn ( fvm::ddt(h) + fvc::div(phiHbyA) - fvm::laplacian(ghrAUf, h) );
phi = phiHbyA + hEqn.flux();
thanks very much for your valuable time.
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