# understanding kEpsilon model source code

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 November 8, 2009, 13:55 understanding kEpsilon model source code #1 New Member   Join Date: Nov 2009 Posts: 12 Rep Power: 10 Hi, I have a question about the implementation of the kEpsilon source code in the file kEpsilon.C (.../src/turbulenceModels/incompressible/RAS/kEpsilon). In line 181 the divDevReff()-function is declared. Can anybody explain the code in line 185 and 186 to me? Thanks!

 November 11, 2009, 23:25 #2 New Member   Nelson HO Join Date: Jul 2009 Posts: 11 Rep Power: 10 Can you post that lines out?

 November 14, 2009, 17:22 #3 New Member   Join Date: Nov 2009 Posts: 12 Rep Power: 10 Hi, I don't understand the following lines: return ( -laplacian(nuEff(), U) -div(nuEff()*dev(grad(U)().T())) ); The whole expression is defined as divDevReff() and should return the source term for the momentum equation. I tried to write it down mathematically but I failed! Thanks for your help!

 November 15, 2009, 05:14 #4 Senior Member     Sebastian Gatzka Join Date: Mar 2009 Location: Frankfurt, Germany Posts: 729 Rep Power: 13 Some people don't know that dev() is a transposition! Well - at least it was me who doesn't know until I was told. But what is this T() ? __________________ Schrödingers wife: "What did you do to the cat? It's half dead!"

 November 15, 2009, 09:21 #5 New Member   Join Date: Nov 2009 Posts: 12 Rep Power: 10 Hmm, are you sure that dev() is a transposition? I think that .T() is a transposition and dev() ist the deviatoric component ( tensor -1/3*(trace tensor)*I ) of the tensor grad(U)().T()? But I wonder if dev() shouldn't be dev2()?

 November 15, 2009, 09:52 #6 Senior Member     Sebastian Gatzka Join Date: Mar 2009 Location: Frankfurt, Germany Posts: 729 Rep Power: 13 Actually your statement makes more sense. I haven't thought about the fact that grad(U) is a tensor and not a vector like U itself! __________________ Schrödingers wife: "What did you do to the cat? It's half dead!"

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