[liuhuafei]

I have a question about the LDUMatrix.

LDUMatrix contains the coefficients, lowerPtr,upperPtr,diagPtr ,and the address reference, uPtr and lPtr.

My questions are as follows:
1) Does the lPtr mean the owner of face and uPtr the neigbour of the face as done in the polyMesh?
In some mesh class in openfoam, owner's index(P)
is lower than neighbor index(N).

2) Does the upperPtr store the contribution of the neighbour cell(N) to the owner cell(P) and
the lowerPtr store the contribution of the owner(P) to the neighbour(N).

In Hoperations.C // H operator
template<class>
tmp<field<type> > lduMatrix::H(const ield<type>& ) const
{
.........
const scalarField& Lower = lower();
const scalarField& Upper = upper();

// Take refereces to addressing
const unallocLabelList& l = lduAddr_.lowerAddr();
const unallocLabelList& u = lduAddr_.upperAddr();

for (register label face=0; face<l.size(); face++) {
Hphi[u[face]] -= Lower[face]*sf[l[face]];
Hphi[l[face]] -= Upper[face]*sf[u[face]];
}
}

From this code, I guess the LowerAddr is owner list and UpperAddr is neighbour list,
Lower is the contribution of the owner (P) to the neighbour (N), Upper is the contribution of
the neighbour(N) to the owner.

if the matrix is
AD1 AU1 AU2 AU3 AU4
AL1 AD2 AU5 AU6 AU7
AL2 AL5 AD3 AU8 AU9
AL3 AL6 AL8 AD4 AU10
AL4 AL7 AL9 AL10 AD5

But in fvMatrix, the implementation of function negSumDiag() is as follows
negSumDiag:
for (register label face=0; face<l.size(); face++)
{
Diag[l[face]] -= Lower[face];
Diag[u[face]] -= Upper[face];
}
Diag[i] should be substract the contribution from all its neighbouring cell, why not the following code?
for (register label face=0; face<l.size(); face++)
{
Diag[l[face]] -= Upper[face];
Diag[u[face]] -= Lower[face];
}


3) For the implementation of FVM laplacian operator,only the fvm.upper is calculated,
why not the fvm.lower?
template<class>
tmp<fvmatrix<type> >
gaussLaplacianScheme<type>::fvmLaplacianUncorrecte d
(
const surfaceScalarField& gammaMagSf,
GeometricField<type,>& vf
)
{
.......
fvMatrix<type>& fvm = tfvm();

fvm.upper() = deltaCoeffs.internalField()*gammaMagSf.internalFie ld();

! why not the fvm.lower()
fvm.negSumDiag();

}

Thanks in advance!
Liu Huafei