# ScalarTransportFoam

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 April 14, 2010, 22:50 ScalarTransportFoam #1 Senior Member   Senthil Kabilan Join Date: Mar 2009 Posts: 113 Rep Power: 9 Hi All, I have a simple question regarding scalarTransportFoam. The code seems to be executing well, but out of the blues, the residual increases (see Time=0.08628 and Time=0.08629) and the starts to settle down. Do you think it has something to do with the way I have setup the problem? Time = 0.08622 DILUPBiCG: Solving for T, Initial residual = 3.20318e-05, Final residual = 2.31572e-11, No Iterations 8 Time = 0.08623 DILUPBiCG: Solving for T, Initial residual = 3.20261e-05, Final residual = 1.51511e-10, No Iterations 7 Time = 0.08624 DILUPBiCG: Solving for T, Initial residual = 3.20143e-05, Final residual = 6.6284e-11, No Iterations 8 Time = 0.08625 DILUPBiCG: Solving for T, Initial residual = 3.20118e-05, Final residual = 2.23166e-10, No Iterations 7 Time = 0.08626 DILUPBiCG: Solving for T, Initial residual = 3.20021e-05, Final residual = 8.8872e-11, No Iterations 8 Time = 0.08627 DILUPBiCG: Solving for T, Initial residual = 3.20002e-05, Final residual = 9.56583e-10, No Iterations 5 Time = 0.08628 DILUPBiCG: Solving for T, Initial residual = 3.19916e-05, Final residual = 8897.06, No Iterations 1001 Time = 0.08629 DILUPBiCG: Solving for T, Initial residual = 0.340886, Final residual = 9.89072e-10, No Iterations 19 Time = 0.0863 DILUPBiCG: Solving for T, Initial residual = 0.170177, Final residual = 1.99834e-10, No Iterations 20 Time = 0.08631 DILUPBiCG: Solving for T, Initial residual = 0.132551, Final residual = 1.36749e-10, No Iterations 21 Time = 0.08632 DILUPBiCG: Solving for T, Initial residual = 0.112358, Final residual = 2.48292e-10, No Iterations 19 Time = 0.08633 DILUPBiCG: Solving for T, Initial residual = 0.0994847, Final residual = 7.72147e-10, No Iterations 18 Time = 0.08634 DILUPBiCG: Solving for T, Initial residual = 0.0891127, Final residual = 5.79845e-10, No Iterations 18 Time = 0.08635 DILUPBiCG: Solving for T, Initial residual = 0.0806057, Final residual = 1.00459e-10, No Iterations 19 Thanks All Senthil

 April 15, 2010, 00:55 #2 Senior Member   Alberto Passalacqua Join Date: Mar 2009 Location: Ames, Iowa, United States Posts: 1,910 Rep Power: 27 Hello. We cannot answer without knowing what problem you are solving. Judging from the residuals something happens at Time = 0.08628, where the final residual is huge (8897.06 !) and the equation reaches the maximum number of iterations. Best, __________________ Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats. OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using.

 April 15, 2010, 11:34 #3 Senior Member   Senthil Kabilan Join Date: Mar 2009 Posts: 113 Rep Power: 9 Hi Alberto, I am using scalarTransportFoam to to simulate diffusion of the acrolein through the rat respiratory system. The mesh is an all tetrahedral mesh with ~13 million elements. The U file in /0 is from a steady state simulation at a constant flow rate. Please let me know if you need further information. Thanks Senthil Below is T file. out1 { type zeroGradient; } out2 { type zeroGradient; } out3 { type zeroGradient; } out4 { type zeroGradient; } inlet { type fixedValue; value uniform 1.38e-06; } Wall { type fixedGradient; gradient uniform 0; } fvSolution file: solvers { T PBiCG { preconditioner DILU; tolerance 1e-09; relTol 0; }; } SIMPLE { nNonOrthogonalCorrectors 0; }

 April 15, 2010, 12:28 #4 Senior Member   Alberto Passalacqua Join Date: Mar 2009 Location: Ames, Iowa, United States Posts: 1,910 Rep Power: 27 Just a couple of general hints. You could check the mesh quality with checkMesh and see if there are very skewed cells. You could also try to perform 1-2 non-orthogonal correctors. Best, __________________ Alberto Passalacqua GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as in both physical and virtual formats. OpenQBMM - An open-source implementation of quadrature-based moment methods. To obtain more accurate answers, please specify the version of OpenFOAM you are using.

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