# Report a bug in LienCubicKELowReSetWallDissipation.H

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 June 20, 2011, 00:37 Report a bug in LienCubicKELowReSetWallDissipation.H #1 Member   Jinbiao Xiong Join Date: Oct 2009 Location: China/Japan Posts: 50 Rep Power: 7 This head file sets the value of epsilon in the near wall cell. In order to consider the possibility that one cell may contain more than one wall-boundary faces. It contains the average function as follow. Code: ``` forAll(patches, patchi) { const fvPatch& curPatch = patches[patchi]; if (isA(curPatch)) { forAll(curPatch, facei) { label faceCelli = curPatch.faceCells()[facei]; // For corner cells (with two boundary or more faces), // epsilon in the near-wall cell are calculated as an average cellBoundaryFaceCount[faceCelli]++; epsilon_[faceCelli] += Cmu75*pow(k_[faceCelli], 1.5) /( kappa_.value()*y_[faceCelli] *(1.0 - exp(-Aepsilon_.value()*yStar_[faceCelli])) ) *exp(-Amu_.value()*sqr(yStar_[faceCelli])); } } } // perform the averaging forAll(patches, patchi) { const fvPatch& curPatch = patches[patchi]; if (isA(curPatch)) { forAll(curPatch, facei) { label faceCelli = curPatch.faceCells()[facei]; epsilon_[faceCelli] /= cellBoundaryFaceCount[faceCelli]; } } }``` For example, the cell i have two wall-boundary faces, then cellBoundaryFaceCount[i]=2. But the epsilon_ in the cell i will be divided by 2 twice. It is to say the epsilon_ is actually divided by 4. To remedy this bug, I replace the code above with Code: ``` forAll(patches, patchi) { const fvPatch& curPatch = patches[patchi]; if (isA(curPatch)) { forAll(curPatch, facei) { label faceCelli = curPatch.faceCells()[facei]; // For corner cells (with two boundary or more faces), // epsilon in the near-wall cell are calculated as an average cellBoundaryFaceCount[faceCelli]++; label n = cellBoundaryFaceCount[faceCelli]; scalar eps_n = Cmu75*pow(k_[faceCelli], 1.5) /( kappa_.value()*y_[faceCelli] *(1.0 - exp(-Aepsilon_.value()*yStar_[faceCelli])) ) *exp(-Amu_.value()*sqr(yStar_[faceCelli])); // eps_ave = [(n-1)*eps_{n-1} + eps_n]/n epsilon_[faceCelli] = ((n-1)*epsilon_[faceCelli] + eps_n) / n;; } } }``` Best, Jinbiao __________________ Jinbiao