Some question about the adjustPhi function
 

Hi,Foamers
I have some questions about the adjustPhi function.

1) At the beginning of the adjustPhi, the value of p.NeedReference determines whether we need adjust the mass flux of boundaries. why?
If pressure field doesn't need the reference level, the adjustion of the boundary flux can be neglected?

2)what is meaning of Up.fixesValue()&& !isA<inletOutletFvPatchVectorField>(Up) ?
What type of boundary is fixedMassOut?


Thanks in advance!





bool Foam::adjustPhi (
surfaceScalarField& phi,
const volVectorField& U,
volScalarField& p
)
{
if (p.needReference())
{
p.boundaryField().updateCoeffs();

scalar massIn = 0.0;
scalar fixedMassOut = 0.0;
scalar adjustableMassOut = 0.0;

forAll (phi.boundaryField(), patchi)
{
const fvPatchVectorField& Up = U.boundaryField()[patchi];
const fvPatchScalarField& phip = phi.boundaryField()[patchi];

if (!isType<processorFvPatchScalarField>(phip))
{
if
(
Up.fixesValue()
&& !isA<inletOutletFvPatchVectorField>(Up)
)
{
forAll(phip, i)
{
if (phip[i] < 0.0)
{
massIn -= phip[i];
}
else
{
fixedMassOut += phip[i];
}
}
}
........................
}
else
{
return false;
}
}