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Problem simulating the temperature rise in a composite material (chtMultiRegionFoam) 

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February 26, 2019, 06:02 
Problem simulating the temperature rise in a composite material (chtMultiRegionFoam)

#1 
Member
Adam
Join Date: Nov 2018
Posts: 31
Rep Power: 4 
I would like to to simulate the temperature evolution in a composite material comprised on fibers in a matrix, however I've reached a point where I am banging my head against the wall! So I am hoping that someone else has faced a similar issue and can point me in the right direction
I would like to compare with a system of known analytical response so I am looking at a slab initially at 300 K, with both left and right extremities at 310 K for time t > 0s. Here is an image of the system, the slab repeats in the vertical direction (cyclicAMI BCs) and is roughly 5% fibers by volume. I'm using the chtMultiRegionFoam solver from OpenFOAM version 5 via BlueCFD.Here is a link to the case on Dropbox. I defined my mesh with gmsh, then import it using "gmshToFoam", run "changeDictionary" then "splitMeshRegions cellZonesOnly overwrite" before running "chtMultiRegionFoam". I am able to run the simulations that converge, however my benchmarking case is not giving me the result that I expect. I would like to confirm that an aluminum slab with aluminum fibers in it gives the same response as a solid aluminum slab; here are the results of four simulations for the temperature at the center of a 2 cm thick slab. I defined probes in OpenFOAM in both phases at the center of the slab.
Does anyone have any insight as to why I am having trouble? I would have expected the orange and yellow curves to converge towards that of a solid block of aluminum (the black curve). 

March 2, 2019, 11:27 

#2 
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Robin Kamenicky
Join Date: Mar 2016
Posts: 65
Rep Power: 7 
Hi Adam,
having a look at your case. Can you send your log files? Can you send the case with no resistance? In the file system/fibres/fvSolution change entry for h Code:
h { solver PCG; preconditioner DIC; tolerance 1e06; relTol 0.1; } Code:
h { solver PCG; preconditioner DIC; tolerance 1e06; relTol 0; } system/matrix/fvSolution If you are interested in temperature evolution in time, use second order scheme for time derivative. Instead of Code:
ddtSchemes { default Euler; } Code:
ddtSchemes { default CrankNicolson 0.9; } Change it for both system/fibres/fvSchemes, system/mastrix/fvSchemes. I can see no time step is defined. Only the first one by deltaT. It is good to setup maxDeltaT and maxDi. Kind regards, Robin 

March 27, 2019, 07:51 

#3 
Member
Adam
Join Date: Nov 2018
Posts: 31
Rep Power: 4 
Hello Robin,
[Edit March 29th: I think it's a problem with a high diffusion number associated to an oversized time step. For a smaller domain and a maxDi of 1 I am able to replicate the analytical solution. Now I'm working on seeing if that scales well to a larger domain.] Thanks a lot for your suggestions. I was away a bit this month, so I've only just had the chance to make those changes to fvSchemes and fvSolution. I used a 1 ms time step. This is the "no resistance" case. Here is the first few iterations from . My whole casefile is here, on dropbox. Code:
/**\  =========    \\ / F ield  OpenFOAM: The Open Source CFD Toolbox   \\ / O peration  Version: 5.x   \\ / A nd  Web: www.OpenFOAM.org   \\/ M anipulation   \**/ /* Windows 32 and 64 bit porting by blueCAPE: http://www.bluecape.com.pt *\  Based on Windows porting (2.0.x v4) by Symscape: http://www.symscape.com  \**/ Build : 5.x963176928289 Exec : C:/PROGRA~1/blueCFD/OpenFOAM5.x/platforms/mingw_w64GccDPInt32Opt/bin/chtMultiRegionFoam.exe Date : Mar 27 2019 Time : 17:04:43 Host : "DESKTOP94MS23F" PID : 8528 I/O : uncollated Case : C:/PROGRA~1/blueCFD/OFUSER~1/run/20190~2/NOTHER~2 nProcs : 1 SigFpe : Enabling floating point exception trapping (FOAM_SIGFPE). fileModificationChecking : Monitoring runtime modified files using timeStampMaster (fileModificationSkew 10) allowSystemOperations : Allowing usersupplied system call operations // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // Create time Create solid mesh for region matrix for time = 0 Create solid mesh for region fibres for time = 0 *** Reading solid mesh thermophysical properties for region matrix Adding to thermos Selecting thermodynamics package { type heSolidThermo; mixture pureMixture; transport constIso; thermo hConst; equationOfState rhoConst; specie specie; energy sensibleEnthalpy; } AMI: Creating addressing and weights between 1381 source faces and 1381 target faces AMI: Patch source sum(weights) min/max/average = 1, 1, 1 AMI: Patch target sum(weights) min/max/average = 1, 1, 1 Adding to radiations Radiation model not active: radiationProperties not found Selecting radiationModel none Adding fvOptions Creating finite volume options from "constant/fvOptions" Selecting finite volume options model type limitTemperature Source: temperatureLimit  selecting all cells  selected 73456 cell(s) with volume 7.6332094e010 *** Reading solid mesh thermophysical properties for region fibres Adding to thermos Selecting thermodynamics package { type heSolidThermo; mixture pureMixture; transport constIso; thermo hConst; equationOfState rhoConst; specie specie; energy sensibleEnthalpy; } AMI: Creating addressing and weights between 148 source faces and 148 target faces AMI: Patch source sum(weights) min/max/average = 1, 1, 1 AMI: Patch target sum(weights) min/max/average = 1, 1, 1 Adding to radiations Radiation model not active: radiationProperties not found Selecting radiationModel none Adding fvOptions Creating finite volume options from "constant/fvOptions" Selecting finite volume options model type limitTemperature Source: temperatureLimit  selecting all cells  selected 20710 cell(s) with volume 3.6679059e011 Region: matrix Diffusion Number mean: 7524.4325 max: 650221.95 Region: fibres Diffusion Number mean: 15009.725 max: 257544.89 > FOAM Warning : From function virtual void Foam::probes::findElements(const Foam::fvMesh&) in file probes/probes.C at line 119 Did not find location (0.01 0.000124 0.0001) in any cell. Skipping location. > FOAM Warning : From function virtual void Foam::probes::findElements(const Foam::fvMesh&) in file probes/probes.C at line 119 Did not find location (0.019925 0.000124 0.0001) in any cell. Skipping location. Region: matrix Diffusion Number mean: 7524.4325 max: 650221.95 Region: fibres Diffusion Number mean: 15009.725 max: 257544.89 Time = 0.001 Pimple iteration 0 Solving for solid region matrix DICPCG: Solving for h, Initial residual = 1, Final residual = 8.7885959e007, No Iterations 85 Min/max T:300 310 Solving for solid region fibres DICPCG: Solving for h, Initial residual = 1, Final residual = 8.3388789e007, No Iterations 27 Min/max T:300 300.70153 ExecutionTime = 2.66 s ClockTime = 3 s Region: matrix Diffusion Number mean: 7524.4325 max: 650221.95 Region: fibres Diffusion Number mean: 15009.725 max: 257544.89 Time = 0.002 Pimple iteration 0 Solving for solid region matrix DICPCG: Solving for h, Initial residual = 0.091379998, Final residual = 8.8626934e007, No Iterations 65 Min/max T:300 310 Solving for solid region fibres DICPCG: Solving for h, Initial residual = 0.22912758, Final residual = 8.3766736e007, No Iterations 24 Min/max T:300 301.31034 ExecutionTime = 2.769 s ClockTime = 3 s Region: matrix Diffusion Number mean: 7524.4325 max: 650221.95 Region: fibres Diffusion Number mean: 15009.725 max: 257544.89 Time = 0.003 Pimple iteration 0 Solving for solid region matrix DICPCG: Solving for h, Initial residual = 0.02080289, Final residual = 9.3586955e007, No Iterations 59 Min/max T:300 310 Solving for solid region fibres DICPCG: Solving for h, Initial residual = 0.11277348, Final residual = 8.3206096e007, No Iterations 23 Min/max T:300 301.83189 ExecutionTime = 2.872 s ClockTime = 3 s Region: matrix Diffusion Number mean: 7524.4325 max: 650221.95 Region: fibres Diffusion Number mean: 15009.725 max: 257544.89 Time = 0.004 Pimple iteration 0 Solving for solid region matrix DICPCG: Solving for h, Initial residual = 0.016267807, Final residual = 9.2612505e007, No Iterations 62 Min/max T:300 310 Solving for solid region fibres DICPCG: Solving for h, Initial residual = 0.07841582, Final residual = 5.6578338e007, No Iterations 23 Min/max T:300 302.29699 ExecutionTime = 2.978 s ClockTime = 3 s Region: matrix Diffusion Number mean: 7524.4325 max: 650221.95 Region: fibres Diffusion Number mean: 15009.725 max: 257544.89 Time = 0.005 Pimple iteration 0 Solving for solid region matrix DICPCG: Solving for h, Initial residual = 0.0146828, Final residual = 9.8860161e007, No Iterations 59 Min/max T:300 310 Solving for solid region fibres DICPCG: Solving for h, Initial residual = 0.057160497, Final residual = 4.6066147e007, No Iterations 23 Min/max T:300 302.70423 ExecutionTime = 3.081 s ClockTime = 3 s Region: matrix Diffusion Number mean: 7524.4325 max: 650221.95 Region: fibres Diffusion Number mean: 15009.725 max: 257544.89 Time = 0.006 Pimple iteration 0 Solving for solid region matrix DICPCG: Solving for h, Initial residual = 0.013493589, Final residual = 9.3242413e007, No Iterations 60 Min/max T:300 310 Solving for solid region fibres DICPCG: Solving for h, Initial residual = 0.046087991, Final residual = 8.5158944e007, No Iterations 22 Min/max T:300 303.0747 ExecutionTime = 3.183 s ClockTime = 3 s Region: matrix Diffusion Number mean: 7524.4325 max: 650221.95 Region: fibres Diffusion Number mean: 15009.725 max: 257544.89 Time = 0.007 Pimple iteration 0 Solving for solid region matrix DICPCG: Solving for h, Initial residual = 0.012048782, Final residual = 8.9506872e007, No Iterations 59 Min/max T:300 310 Solving for solid region fibres DICPCG: Solving for h, Initial residual = 0.037440288, Final residual = 6.4396571e007, No Iterations 22 Min/max T:300 303.40641 ExecutionTime = 3.286 s ClockTime = 3 s Region: matrix Diffusion Number mean: 7524.4325 max: 650221.95 Region: fibres Diffusion Number mean: 15009.725 max: 257544.89 Time = 0.008 Pimple iteration 0 Solving for solid region matrix DICPCG: Solving for h, Initial residual = 0.0114714, Final residual = 9.2839842e007, No Iterations 59 Min/max T:300 310 Solving for solid region fibres DICPCG: Solving for h, Initial residual = 0.032033575, Final residual = 5.2419503e007, No Iterations 22 Min/max T:300 303.71249 ExecutionTime = 3.391 s ClockTime = 3 s Region: matrix Diffusion Number mean: 7524.4325 max: 650221.95 Region: fibres Diffusion Number mean: 15009.725 max: 257544.89 Time = 0.009 Pimple iteration 0 Solving for solid region matrix DICPCG: Solving for h, Initial residual = 0.010345927, Final residual = 9.4233542e007, No Iterations 58 Min/max T:300 310 Solving for solid region fibres DICPCG: Solving for h, Initial residual = 0.027442799, Final residual = 7.7909506e007, No Iterations 21 Min/max T:300 303.98976 ExecutionTime = 3.493 s ClockTime = 4 s Region: matrix Diffusion Number mean: 7524.4325 max: 650221.95 Region: fibres Diffusion Number mean: 15009.725 max: 257544.89 Time = 0.01 Last edited by Adam_K; March 29, 2019 at 00:58. 

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