pEqn.H

if (!pimple.SIMPLErho())
{
    rho = thermo.rho();
}

// Thermodynamic density needs to be updated by psi*d(p) after the
// pressure solution
const volScalarField psip0(psi*p);

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

surfaceScalarField phig(-rhorAUf*ghf*fvc::snGrad(rho)*mesh.magSf());

surfaceScalarField phiHbyA
(
    "phiHbyA",
    (
        fvc::flux(rho*HbyA)
      + MRF.zeroFilter(rhorAUf*fvc::ddtCorr(rho, U, phi))
    )
  + phig
);

fvc::makeRelative(phiHbyA, rho, U);
MRF.makeRelative(fvc::interpolate(rho), phiHbyA);

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

fvScalarMatrix p_rghDDtEqn
(
    fvc::ddt(rho) + psi*correction(fvm::ddt(p_rgh))
  + fvc::div(phiHbyA)
 ==
    parcels.Srho()
  + surfaceFilm.Srho()
  + fvOptions(psi, p_rgh, rho.name())
);

while (pimple.correctNonOrthogonal())
{
    fvScalarMatrix p_rghEqn
    (
        p_rghDDtEqn
      - fvm::laplacian(rhorAUf, p_rgh)
    );

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

    if (pimple.finalNonOrthogonalIter())
    {
        phi = phiHbyA + p_rghEqn.flux();

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

        U = HbyA + rAU*fvc::reconstruct((p_rghEqn.flux() + phig)/rhorAUf);
        U.correctBoundaryConditions();
        fvOptions.correct(U);
        K = 0.5*magSqr(U);
    }
}

p = p_rgh + rho*gh;

// Thermodynamic density update
thermo.correctRho(psi*p - psip0);

#include "rhoEqn.H"
#include "compressibleContinuityErrs.H"

if (pressureControl.limit(p))
{
    p.correctBoundaryConditions();
    rho = thermo.rho();
    p_rgh = p - rho*gh;
}
else if (pimple.SIMPLErho())
{
    rho = thermo.rho();
}

// Correct rhoUf if the mesh is moving
fvc::correctRhoUf(rhoUf, rho, U, phi);

if (thermo.dpdt())
{
    dpdt = fvc::ddt(p);

    if (mesh.moving())
    {
        dpdt -= fvc::div(fvc::meshPhi(rho, U), p);
    }
}