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Source term in the compressible momentum equation 

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April 9, 2015, 18:13 
Source term in the compressible momentum equation

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Daniel Duque
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Location: ETSIN, Madrid
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Hello everyone.
I'm studying this piece of code for the source term in the momentum equation. It's a laminar, compressible simulation in which mu is NOT constant. Code:
tmp<fvVectorMatrix> laminar::divDevRhoReff(volVectorField& U) const { return (  fvm::laplacian(muEff(), U)  fvc::div(muEff()*dev2(T(fvc::grad(U)))) ); } Laplacian( mu U) + div ( mu ( gradU^t  (2/3) divU I ) ) If mu was constant I would be happy, even if the second term is mathematically equal to (1/3) grad divU. There is surely some reason to write it this way. But I am concerned with the first term, which should be: div ( mu gradU) Perhaps that's what fvm::laplacian(muEff(), U) is ?? (It could also be mu Laplacian U, which wouldn't be good.) Btw, it seems the fluid is supposed to be Stokesian, so that lamba+(2/3) mu =0, am I right? Thanks! Daniel 

April 9, 2015, 18:33 

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ali alkebsi
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April 10, 2015, 05:58 

#3 
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Daniel Duque
Join Date: Jan 2011
Location: ETSIN, Madrid
Posts: 28
Rep Power: 15 

Tags 
compressible flow, laplacian operator, momentum equation, momentum source, navierstokes solver 
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