pEqn.H

{
    surfaceScalarField faceMask(localMin<scalar>(mesh).interpolate(cellMask));

    volScalarField rAU(1.0/UEqn.A());
    surfaceScalarField rhorAUf("rhorAUf", faceMask*fvc::interpolate(rho*rAU));
    volVectorField HbyA("HbyA", U);
    HbyA = constrainHbyA(cellMask*rAU*UEqn.H(), U, p);
    tUEqn.clear();

    bool closedVolume = false;

    surfaceScalarField phiHbyA("phiHbyA", fvc::interpolate(rho)*fvc::flux(HbyA));
    MRF.makeRelative(fvc::interpolate(rho), phiHbyA);

    // Update the pressure BCs to ensure flux consistency
    constrainPressure(p, rho, U, phiHbyA, rhorAUf, MRF);

    if (simple.transonic())
    {
        surfaceScalarField phid
        (
            "phid",
            (fvc::interpolate(psi)/fvc::interpolate(rho))*phiHbyA
        );

        phiHbyA -= fvc::interpolate(psi*p)*phiHbyA/fvc::interpolate(rho);

        while (simple.correctNonOrthogonal())
        {
            fvScalarMatrix pEqn
            (
                fvc::div(phiHbyA)
              + fvm::div(phid, p)
              - fvm::laplacian(rhorAUf, p)
            ==
                fvOptions(psi, p, rho.name())
            );

            // Relax the pressure equation to ensure diagonal-dominance
            pEqn.relax();

            pEqn.setReference
            (
                pressureControl.refCell(),
                pressureControl.refValue()
            );

            pEqn.solve();

            if (simple.finalNonOrthogonalIter())
            {
                phi = phiHbyA + pEqn.flux();
            }
        }
    }
    else
    {
        closedVolume = adjustPhi(phiHbyA, U, p);

        if (adjustFringe)
        {
            oversetAdjustPhi(phiHbyA, U);
        }

        while (simple.correctNonOrthogonal())
        {
            fvScalarMatrix pEqn
            (
                fvc::div(phiHbyA)
              - fvm::laplacian(rhorAUf, p)
            ==
                fvOptions(psi, p, rho.name())
            );

            pEqn.setReference
            (
                pressureControl.refCell(),
                pressureControl.refValue()
            );

            pEqn.solve();

            if (simple.finalNonOrthogonalIter())
            {
                phi = phiHbyA + pEqn.flux();
            }
        }
    }

    #include "incompressible/continuityErrs.H"

    // Explicitly relax pressure for momentum corrector
    p.relax();

    volVectorField gradP(fvc::grad(p));

    U = HbyA - rAU*cellMask*gradP;
    U.correctBoundaryConditions();
    fvOptions.correct(U);


    bool pLimited = pressureControl.limit(p);

    // For closed-volume cases adjust the pressure and density levels
    // to obey overall mass continuity
    if (closedVolume)
    {
        p += (initialMass - fvc::domainIntegrate(psi*p))
            /fvc::domainIntegrate(psi);
    }

    if (pLimited || closedVolume)
    {
        p.correctBoundaryConditions();
    }

    rho = thermo.rho();

    if (!simple.transonic())
    {
        rho.relax();
    }
}