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twoPhaseEulerFoam: Add partial-elimination to phase flux and velocity correction
Improves stability and convergence of systems in which drag dominates e.g. small particles in high-speed gas flow. Additionally a new ddtPhiCorr strategy is included in which correction is applied only where the phases are nearly pure. This reduces staggering patters near the free-surface of bubble-column simulations.
This commit is contained in:
Henry
@ -1,3 +1,5 @@
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// --- Pressure corrector loop
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while (pimple.correct())
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{
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surfaceScalarField alpha1f("alpha1f", fvc::interpolate(alpha1));
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surfaceScalarField alpha2f("alpha2f", scalar(1) - alpha1f);
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339
applications/solvers/multiphase/twoPhaseEulerFoam/pEqnElim.H
Normal file
339
applications/solvers/multiphase/twoPhaseEulerFoam/pEqnElim.H
Normal file
@ -0,0 +1,339 @@
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surfaceScalarField alpha1f("alpha1f", fvc::interpolate(alpha1));
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surfaceScalarField alpha2f("alpha2f", scalar(1) - alpha1f);
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rAU1 = 1.0/U1Eqn.A();
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rAU2 = 1.0/U2Eqn.A();
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surfaceScalarField rAlphaAU1f(fvc::interpolate(alpha1*rho1*rAU1));
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surfaceScalarField rAlphaAU2f(fvc::interpolate(alpha2*rho2*rAU2));
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// --- Pressure corrector loop
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while (pimple.correct())
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{
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volVectorField HbyA1
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(
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IOobject::groupName("HbyA", phase1.name()),
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U1
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);
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HbyA1 = rAU1*U1Eqn.H();
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volVectorField HbyA2
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(
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IOobject::groupName("HbyA", phase2.name()),
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U2
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);
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HbyA2 = rAU2*U2Eqn.H();
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// Phase pressure flux (e.g. due to particle-particle pressure)
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surfaceScalarField phiF1
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(
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"phiF1",
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fvc::interpolate(rAU1*phase1.turbulence().pPrime())
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*fvc::snGrad(alpha1)*mesh.magSf()
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);
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// Phase-2 pressure flux (e.g. due to particle-particle pressure)
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surfaceScalarField phiF2
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(
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"phiF2",
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fvc::interpolate(rAU2*phase2.turbulence().pPrime())
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*fvc::snGrad(alpha2)*mesh.magSf()
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);
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// Mean density for buoyancy force and p_rgh -> p
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volScalarField rho("rho", fluid.rho());
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// Add Buoyancy force
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{
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surfaceScalarField ghSnGradRho(ghf*fvc::snGrad(rho)*mesh.magSf());
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phiF1 +=
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rAlphaAU1f
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*(
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ghSnGradRho
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- alpha2f*fvc::interpolate(rho1 - rho2)*(g & mesh.Sf())
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)/fvc::interpolate(rho1);
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phiF2 +=
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rAlphaAU2f
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*(
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ghSnGradRho
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- alpha1f*fvc::interpolate(rho2 - rho1)*(g & mesh.Sf())
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)/fvc::interpolate(rho2);
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}
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// ddtPhiCorr filter -- only apply in pure(ish) phases
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surfaceScalarField alpha1fBar(fvc::interpolate(fvc::average(alpha1f)));
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surfaceScalarField phiCorrCoeff1(pos(alpha1fBar - 0.99));
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surfaceScalarField phiCorrCoeff2(pos(0.01 - alpha1fBar));
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// Set ddtPhiCorr to 0 on non-coupled boundaries
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forAll(mesh.boundary(), patchi)
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{
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if
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(
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!mesh.boundary()[patchi].coupled()
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|| isA<cyclicAMIFvPatch>(mesh.boundary()[patchi])
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)
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{
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phiCorrCoeff1.boundaryField()[patchi] = 0;
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phiCorrCoeff2.boundaryField()[patchi] = 0;
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}
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}
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// Phase-1 predicted flux
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surfaceScalarField phiHbyA1
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(
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IOobject::groupName("phiHbyA", phase1.name()),
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(fvc::interpolate(HbyA1) & mesh.Sf())
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+ phiCorrCoeff1*rAlphaAU1f
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*(
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mrfZones.absolute(phi1.oldTime())
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- (fvc::interpolate(U1.oldTime()) & mesh.Sf())
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)/runTime.deltaT()
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- phiF1
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);
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// Phase-2 predicted flux
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surfaceScalarField phiHbyA2
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(
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IOobject::groupName("phiHbyA", phase2.name()),
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(fvc::interpolate(HbyA2) & mesh.Sf())
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+ phiCorrCoeff2*rAlphaAU2f
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*(
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mrfZones.absolute(phi2.oldTime())
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- (fvc::interpolate(U2.oldTime()) & mesh.Sf())
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)/runTime.deltaT()
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- phiF2
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);
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// Face-drag coefficients
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surfaceScalarField D1f(fvc::interpolate(rAU1*dragCoeff));
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surfaceScalarField D2f(fvc::interpolate(rAU2*dragCoeff));
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// Construct the mean predicted flux
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// including explicit drag contributions based on absolute fluxes
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surfaceScalarField phiHbyA
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(
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"phiHbyA",
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alpha1f*(phiHbyA1 + D1f*mrfZones.absolute(phi2))
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+ alpha2f*(phiHbyA2 + D2f*mrfZones.absolute(phi1))
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);
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mrfZones.makeRelative(phiHbyA);
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// Construct pressure "diffusivity"
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surfaceScalarField rAUf
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(
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"rAUf",
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mag
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(
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alpha1f*rAlphaAU1f/fvc::interpolate(rho1)
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+ alpha2f*rAlphaAU2f/fvc::interpolate(rho2)
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)
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);
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// Update the fixedFluxPressure BCs to ensure flux consistency
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setSnGrad<fixedFluxPressureFvPatchScalarField>
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(
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p_rgh.boundaryField(),
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(
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phiHbyA.boundaryField()
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- mrfZones.relative
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(
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alpha1f.boundaryField()
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*(mesh.Sf().boundaryField() & U1.boundaryField())
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+ alpha2f.boundaryField()
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*(mesh.Sf().boundaryField() & U2.boundaryField())
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)
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)/(mesh.magSf().boundaryField()*rAUf.boundaryField())
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);
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tmp<fvScalarMatrix> pEqnComp1;
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tmp<fvScalarMatrix> pEqnComp2;
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// Construct the compressibility parts of the pressure equation
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if (pimple.transonic())
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{
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surfaceScalarField phid1
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(
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IOobject::groupName("phid", phase1.name()),
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fvc::interpolate(psi1)*phi1
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);
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surfaceScalarField phid2
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(
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IOobject::groupName("phid", phase2.name()),
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fvc::interpolate(psi2)*phi2
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);
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pEqnComp1 =
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(
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contErr1
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- fvc::Sp(fvc::ddt(alpha1) + fvc::div(alphaPhi1), rho1)
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)/rho1
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+ (alpha1/rho1)*correction
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(
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psi1*fvm::ddt(p_rgh)
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+ fvm::div(phid1, p_rgh) - fvm::Sp(fvc::div(phid1), p_rgh)
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);
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deleteDemandDrivenData(pEqnComp1().faceFluxCorrectionPtr());
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pEqnComp1().relax();
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pEqnComp2 =
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(
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contErr2
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- fvc::Sp(fvc::ddt(alpha2) + fvc::div(alphaPhi2), rho2)
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)/rho2
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+ (alpha2/rho2)*correction
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(
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psi2*fvm::ddt(p_rgh)
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+ fvm::div(phid2, p_rgh) - fvm::Sp(fvc::div(phid2), p_rgh)
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);
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deleteDemandDrivenData(pEqnComp2().faceFluxCorrectionPtr());
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pEqnComp2().relax();
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}
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else
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{
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pEqnComp1 =
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(
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contErr1
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- fvc::Sp(fvc::ddt(alpha1) + fvc::div(alphaPhi1), rho1)
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)/rho1
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+ (alpha1*psi1/rho1)*correction(fvm::ddt(p_rgh));
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pEqnComp2 =
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(
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contErr2
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- fvc::Sp(fvc::ddt(alpha2) + fvc::div(alphaPhi2), rho2)
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)/rho2
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+ (alpha2*psi2/rho2)*correction(fvm::ddt(p_rgh));
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}
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// Cache p prior to solve for density update
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volScalarField p_rgh_0(p_rgh);
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// Iterate over the pressure equation to correct for non-orthogonality
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while (pimple.correctNonOrthogonal())
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{
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// Construct the transport part of the pressure equation
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fvScalarMatrix pEqnIncomp
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(
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fvc::div(phiHbyA)
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- fvm::laplacian(rAUf, p_rgh)
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);
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solve
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(
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pEqnComp1() + pEqnComp2() + pEqnIncomp,
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mesh.solver(p_rgh.select(pimple.finalInnerIter()))
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);
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// Correct fluxes and velocities on last non-orthogonal iteration
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if (pimple.finalNonOrthogonalIter())
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{
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phi = phiHbyA + pEqnIncomp.flux();
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surfaceScalarField mSfGradp("mSfGradp", pEqnIncomp.flux()/rAUf);
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// Partial-elimination phase-flux corrector
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{
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surfaceScalarField phi1s
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(
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phiHbyA1 + rAlphaAU1f*mSfGradp/fvc::interpolate(rho1)
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);
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surfaceScalarField phi2s
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(
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phiHbyA2 + rAlphaAU2f*mSfGradp/fvc::interpolate(rho2)
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);
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surfaceScalarField phir
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(
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((phi1s + D1f*phi2s) - (phi2s + D2f*phi1s))/(1 - D1f*D2f)
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);
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phi1.boundaryField() ==
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mrfZones.relative
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(
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mesh.Sf().boundaryField() & U1.boundaryField()
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);
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phi1 = phi + alpha2f*phir;
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phi2.boundaryField() ==
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mrfZones.relative
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(
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mesh.Sf().boundaryField() & U2.boundaryField()
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);
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phi2 = phi - alpha1f*phir;
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}
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// Compressibility correction for phase-fraction equations
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fluid.dgdt() =
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(
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alpha1*(pEqnComp2 & p_rgh)
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- alpha2*(pEqnComp1 & p_rgh)
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);
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// Optionally relax pressure for velocity correction
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p_rgh.relax();
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// Update the static pressure
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p = max(p_rgh + rho*gh, pMin);
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p_rgh = p - rho*gh;
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mSfGradp = pEqnIncomp.flux()/rAUf;
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// Partial-elimination phase-velocity corrector
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{
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volVectorField U1s
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(
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HbyA1
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+ fvc::reconstruct
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(
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rAlphaAU1f*mSfGradp/fvc::interpolate(rho1)
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- phiF1
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)
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);
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volVectorField U2s
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(
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HbyA2
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+ fvc::reconstruct
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(
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rAlphaAU2f*mSfGradp/fvc::interpolate(rho2)
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- phiF2
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)
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);
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volScalarField D1(rAU1*dragCoeff);
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volScalarField D2(rAU2*dragCoeff);
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U = alpha1*(U1s + D1*U2) + alpha2*(U2s + D2*U1);
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volVectorField Ur(((1 - D2)*U1s - (1 - D1)*U2s)/(1 - D1*D2));
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U1 = U + alpha2*Ur;
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U1.correctBoundaryConditions();
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fvOptions.correct(U1);
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U2 = U - alpha1*Ur;
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U2.correctBoundaryConditions();
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fvOptions.correct(U2);
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U = fluid.U();
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}
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}
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}
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// Update densities from change in p
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rho1 += psi1*(p_rgh - p_rgh_0);
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rho2 += psi2*(p_rgh - p_rgh_0);
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// Update the phase kinetic energies
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K1 = 0.5*magSqr(U1);
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K2 = 0.5*magSqr(U2);
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// Update the pressure time-derivative if required
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if (thermo1.dpdt() || thermo2.dpdt())
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{
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dpdt = fvc::ddt(p);
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}
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}
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@ -90,16 +90,10 @@ int main(int argc, char *argv[])
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- (fvOptions(alpha2, rho2)&rho2)
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);
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#include "UEqns.H"
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#include "EEqns.H"
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// --- Pressure corrector loop
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while (pimple.correct())
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{
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#include "pEqn.H"
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}
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//#include "pEqn.H"
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#include "pEqnElim.H"
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#include "DDtU.H"
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if (pimple.turbCorr())
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@ -2,7 +2,7 @@
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========= |
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\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
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\\ / O peration |
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\\ / A nd | Copyright (C) 2012-2014 OpenFOAM Foundation
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\\ / A nd | Copyright (C) 2012-2015 OpenFOAM Foundation
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\\/ M anipulation |
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-------------------------------------------------------------------------------
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License
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@ -218,6 +218,17 @@ void Foam::MRFZoneList::makeRelative(surfaceScalarField& phi) const
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}
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Foam::tmp<Foam::surfaceScalarField> Foam::MRFZoneList::relative
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(
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const tmp<surfaceScalarField>& phi
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) const
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{
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tmp<surfaceScalarField> rphi(phi.ptr());
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makeRelative(rphi());
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return rphi;
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}
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Foam::tmp<Foam::FieldField<Foam::fvsPatchField, Foam::scalar> >
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Foam::MRFZoneList::relative
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(
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@ -266,6 +277,17 @@ void Foam::MRFZoneList::makeAbsolute(surfaceScalarField& phi) const
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}
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Foam::tmp<Foam::surfaceScalarField> Foam::MRFZoneList::absolute
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(
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const tmp<surfaceScalarField>& phi
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) const
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{
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tmp<surfaceScalarField> rphi(phi.ptr());
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makeAbsolute(rphi());
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return rphi;
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}
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void Foam::MRFZoneList::makeAbsolute
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(
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const surfaceScalarField& rho,
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@ -2,7 +2,7 @@
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========= |
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\\ / F ield | OpenFOAM: The Open Source CFD Toolbox
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\\ / O peration |
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\\ / A nd | Copyright (C) 2012-2014 OpenFOAM Foundation
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\\ / A nd | Copyright (C) 2012-2015 OpenFOAM Foundation
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\\/ M anipulation |
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-------------------------------------------------------------------------------
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License
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@ -118,12 +118,15 @@ public:
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//- Make the given absolute velocity relative within the MRF region
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void makeRelative(volVectorField& U) const;
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//- Make the given relative velocity absolute within the MRF region
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void makeAbsolute(volVectorField& U) const;
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//- Make the given absolute flux relative within the MRF region
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void makeRelative(surfaceScalarField& phi) const;
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//- Return the given absolute flux relative within the MRF region
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tmp<surfaceScalarField> relative
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(
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const tmp<surfaceScalarField>& phi
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) const;
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//- Return the given absolute boundary flux relative within
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// the MRF region
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tmp<FieldField<fvsPatchField, scalar> > relative
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@ -138,9 +141,18 @@ public:
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surfaceScalarField& phi
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) const;
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//- Make the given relative velocity absolute within the MRF region
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void makeAbsolute(volVectorField& U) const;
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//- Make the given relative flux absolute within the MRF region
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void makeAbsolute(surfaceScalarField& phi) const;
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//- Return the given relative flux absolute within the MRF region
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tmp<surfaceScalarField> absolute
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(
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const tmp<surfaceScalarField>& phi
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) const;
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//- Make the given relative mass-flux absolute within the MRF region
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void makeAbsolute
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(
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