adding gravity term in pisoFoam
 

Hi

I'm being set up the LES model for the channel flows.

At first, I refer to channelFoam. However, in its driving force for the flows is pressure gradients. but I would like to consider the gravity term for the driving force.

So, I added a new term to the original pisoFoam. But I'm not sure my attempt.
My code is as follows. I'll thank you any advice.

## pisoFoam.c
while (runTime.loop())
{
Info<< "Time = " << runTime.timeName() << nl << endl;

#include "readPISOControls.H"
#include "CourantNo.H"

// Pressure-velocity PISO corrector
{
// Momentum predictor

fvVectorMatrix UEqn
(
fvm::ddt(U)
+ fvm::div(phi, U)
+ turbulence->divDevReff(U)
// ==
// Gravity
);

UEqn.relax();

if (momentumPredictor)
{
solve(UEqn == -fvc::grad(p)+Gravity2); //corrected
}

// --- PISO loop

for (int corr=0; corr<nCorr; corr++)
{
volScalarField rAU(1.0/UEqn.A());

volVectorField HbyA("HbyA", U);
HbyA = rAU*(UEqn.H()+Gravity2); //corrected
surfaceScalarField phiHbyA
(
"phiHbyA",
(fvc::interpolate(HbyA) & mesh.Sf())
+ fvc::interpolate(rAU)*fvc::ddtCorr(U, phi)
);

adjustPhi(phiHbyA, U, p);

// Non-orthogonal pressure corrector loop
for (int nonOrth=0; nonOrth<=nNonOrthCorr; nonOrth++)
{
// Pressure corrector

fvScalarMatrix pEqn
(
fvm::laplacian(rAU, p) == fvc::div(phiHbyA)
);

pEqn.setReference(pRefCell, pRefValue);

if
(
corr == nCorr-1
&& nonOrth == nNonOrthCorr
)
{
pEqn.solve(mesh.solver("pFinal"));
}
else
{
pEqn.solve();
}

if (nonOrth == nNonOrthCorr)
{
phi = phiHbyA - pEqn.flux();
}
}

// #include "continuityErrs.H"

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

##createFiedls.H

volVectorField Gravity2
(
IOobject
(
"Gravity2",
runTime.constant(),
mesh,
IOobject::NO_READ,
IOobject::NO_WRITE,
false
),
mesh,
dimensionedVector("Gravity2", dimensionSet(0,1,-2,0,0,0,0),vector(0,-9.81,0))
);