fvc::reconstruct( ) algorithm
Hi Foamers,
I am trying to figure out how the fvc::reconstruct( ) algorithm works. My first thought was: Sum up the facefluxes multiplied with the facenormal over a cell and divide it by the sum of the magnitude of the facevector components of every face of the cell. The algorithm in the "fvcReconstruct.C" file seems far more complex then my thought: inv(surfaceSum(sqr(mesh.Sf())/mesh.magSf())) & surfaceSum((mesh.Sf()/mesh.magSf())*ssf) The second line is what I expected, but the first line is a little mystery to me. Can anybody explain this to my, please? Rainer 
Just a guess... it looks like it might be nonorthogonal correction...?

Rainer, I agree with your description. The first line finds one over the square of the components of the area. The second line has the the components of the area in the numerator, so the result is just one over the area times the sum of what ever you are reconstructing. This is what you want for a faceareaweighted average.
There is another post by Henry which is relevant here: http://www.cfdonline.com/Forums/ope...integrate.html Kevin 
I am also puzzled by what fvc:reconstruct does. Has anyone here figured what it does? It seems it is not based on any mathematical identity (like Gauss theorem), but some sort of approximation.

fvc::reconstruct explaination
1 Attachment(s)
Hello,
I have had a look at the fvc::reconstruct method. Please find attached an attempt to explain it. Cheers, Thibault 
Thibault, excellent! Thank you for you work! Currently I am working on improving my model introducing a reconstruction for them... So hope to find some advantage on using it, will post some general conclusions.

Hi makaveli_lcf,
Did you find any advantage using fvc::reconstruct ? In my experience, using fvc::reconstruct seems too dissipative? need to find out what cause the dissipation, maybe due to the faceweighted averaging ? Just curious, did you find anything similar? Quote:

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