[ata]

Hi FOAMers
can any one tell me what is the mesh.surfaceInterpolation::deltaCoeffs() in alphaCourantNo.H file of interFoam solver?
I mean what are mesh.surfaceInterpolation and deltaCoeffs()?
best regards

[santiagomarquezd]

Hi, looking at surfaceInterpolation.C you have that deltaCoeffs are

00235     // Set local references to mesh data
00236     const volVectorField& C = mesh_.C();
00237     const unallocLabelList& owner = mesh_.owner();
00238     const unallocLabelList& neighbour = mesh_.neighbour();
00239     const surfaceVectorField& Sf = mesh_.Sf();
00240     const surfaceScalarField& magSf = mesh_.magSf();
00241 
00242     forAll(owner, facei)
00243     {
00244         vector delta = C[neighbour[facei]] - C[owner[facei]];
00245         vector unitArea = Sf[facei]/magSf[facei];
00246 
00247         // Standard cell-centre distance form
00248         //DeltaCoeffs[facei] = (unitArea & delta)/magSqr(delta);
00249 
00250         // Slightly under-relaxed form
00251         //DeltaCoeffs[facei] = 1.0/mag(delta);
00252 
00253         // More under-relaxed form
00254         //DeltaCoeffs[facei] = 1.0/(mag(unitArea & delta) + VSMALL);
00255 
00256         // Stabilised form for bad meshes
00257         DeltaCoeffs[facei] = 1.0/max(unitArea & delta, 0.05*mag(delta));
00258     }

delta=C_N-C_P
unitArea = Sf/|Sf|
deltaCoeffs = 1.0/max(unitArea & delta, 0.05*mag(delta))

where & is the dot product. Then they're the reciprocal of center to center distances projected over the face normal (with a stabilization factor) of cells' shared face.

Regards.

[ata]

Thank you very much again