CFD Online Discussion Forums - Different implementation pEqn.H in pimpleFoam vs interPhaseChangeFoam

Hello,

I am confusing about the implementation of pEqn.H in pimpleFoam vs interPhaseChangeFoam:

From Non-orthogonal pressure corrector loop, pimpleFoam is written:

Code:



// Non-orthogonal pressure corrector loop

while (pimple.correctNonOrthogonal())

{

    // Pressure corrector

    fvScalarMatrix pEqn

    (

        fvm::laplacian(rAUf, p) == fvc::div(phiHbyA)

    );



    pEqn.setReference(pRefCell, pRefValue);



    pEqn.solve(mesh.solver(p.select(pimple.finalInnerIter())));



    if (pimple.finalNonOrthogonalIter())

    {

        phi = phiHbyA - pEqn.flux();

    }

}



#include "continuityErrs.H"



// Explicitly relax pressure for momentum corrector

p.relax();



U = HbyA - rAU*fvc::grad(p);

U.correctBoundaryConditions();

fvOptions.correct(U);

Since in interPhaseChangeFoam is:

Code:

    while (pimple.correctNonOrthogonal())

    {

        fvScalarMatrix p_rghEqn

        (

            fvc::div(phiHbyA) - fvm::laplacian(rAUf, p_rgh)

          - (vDotvP - vDotcP)*(pSat - rho*gh) + fvm::Sp(vDotvP - vDotcP, p_rgh)

        );



        p_rghEqn.setReference(pRefCell, pRefValue);



        p_rghEqn.solve(mesh.solver(p_rgh.select(pimple.finalInnerIter())));



        if (pimple.finalNonOrthogonalIter())

        {

            phi = phiHbyA + p_rghEqn.flux();



            U = HbyA + rAU*fvc::reconstruct((phig + p_rghEqn.flux())/rAUf);

            U.correctBoundaryConditions();

            fvOptions.correct(U);

        }

    }



    p == p_rgh + rho*gh;



    if (p_rgh.needReference())

    {

        p += dimensionedScalar

        (

            "p",

            p.dimensions(),

            pRefValue - getRefCellValue(p, pRefCell)

        );

        p_rgh = p - rho*gh;

    }

}

Two main differents and questions:

1) In pimpleFoam U is solved outside the while condition, since in interPhaseChangeFoam is inside it.
My firts thought was that the U is not solved in interPhaseChangeFoam if we set nonOrthogonalCorrector = 0, what is very strange. But seing the solutionControl Class (in particular solutionControlI.H) I find that is added 1 to nNonOrthCorr, therefore I guess that non-Othogonal correction is solved at least one. My questions are:

a) am I correct on this?

b) is any difference in the final solution between putting U reconstruction inside or outside the [CODE] "while" ?

2) In interPhaseChangeFoam the p.relax() does not exist, therefore if we use pimple Loops outerCorr > 1, it is not applied relaxion factors.

c) Does anybody knows why is not p.relax() in the code, or if I miss somewhere where is applied it?

Thank you to anyone who can help me.

Regards,