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compressibleInterFoam: Negative temperature or printStack |
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June 30, 2020, 13:03 |
compressibleInterFoam: Negative temperature or printStack
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#1 |
New Member
Robson Leo Pachaly
Join Date: Oct 2019
Posts: 3
Rep Power: 7 |
Hello,
I'm trying to simulate a system with several inflows and one outflow that changes the flow rate during the simulation. I want to know the pressurization in three points when the outflow is reduced (see image attached and the U file). There is also some connections to the atmosphere where I am not interested in pressurization. The image attached shows the geometry of the system (don't judge the mesh, it's just an old mesh for demonstration). I usually get two errors when I'm trying to solve this system: negative temperature and printStack error. What I've tried and not worked:
When I consider the atm locations as wall instead of atmosphere BC's, the model runs. But I really don't want this extra pressurization at the points where I have atm (see image). I want to use the kOmegaSST as turbulence model in a near future. But at this moment I'm turning off the turbulence model. My BC's for p, p_rgh, T, and U are: Code:
FoamFile { version 2.0; format ascii; class volScalarField; location "0"; object p_rgh; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [1 -1 -2 0 0 0 0]; internalField uniform 100000; boundaryField { walls { type calculated; value $internalField; } atm { type calculated; value $internalField; } inletTop { type calculated; value $internalField; } inletBottom { type calculated; value $internalField; } inletPipe2 { type calculated; value $internalField; } inletPipe3 { type calculated; value $internalField; } inletPipe1 { type calculated; value $internalField; } outlet { type calculated; value $internalField; } } Code:
FoamFile { version 2.0; format ascii; class volScalarField; object p_rgh; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [1 -1 -2 0 0 0 0]; internalField uniform 1e5; boundaryField { outlet { type zeroGradient; } ".*" { type fixedFluxPressure; value uniform 1e5; } } Code:
FoamFile { version 2.0; format ascii; class volScalarField; location "0"; object T; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 0 0 1 0 0 0]; internalField uniform 300; boundaryField { walls { type zeroGradient; } atm { type inletOutlet; inletValue uniform 300; } inletTop { type zeroGradient; } inletBottom { type zeroGradient; } inletPipe1 { type zeroGradient; } inletPipe2 { type zeroGradient; } inletPipe3 { type zeroGradient; } outlet { type zeroGradient; } } Code:
FoamFile { version 2.0; format ascii; class volVectorField; object U; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 1 -1 0 0 0 0]; internalField uniform (0 0 0); boundaryField { walls { type noSlip; } atm { type pressureInletOutletVelocity; value $internalField; } inletTop { type flowRateInletVelocity; volumetricFlowRate constant 7.7; } inletBottom { type flowRateInletVelocity; volumetricFlowRate constant 7.2; } inletPipe1 { type flowRateInletVelocity; volumetricFlowRate constant 3.4; } inletPipe2 { type flowRateInletVelocity; volumetricFlowRate constant 3.4; } inletPipe3 { type flowRateInletVelocity; volumetricFlowRate constant 3.4; } outlet { type flowRateOutletVelocity; volumetricFlowRate table ( (0 27.5) (59 27.5) (60 12) (180 12) (181 27.5) (240 27.5) ); } } Code:
FoamFile { version 2.0; format ascii; class dictionary; location "system"; object fvSolution; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // solvers { "alpha.water.*" { nAlphaCorr 1; nAlphaSubCycles 2; cAlpha 1; MULESCorr no; nLimiterIter 5; solver smoothSolver; smoother symGaussSeidel; tolerance 1e-10; relTol 0; } "pcorr.*" { solver PCG; preconditioner { preconditioner GAMG; tolerance 1e-12; relTol 0; smoother DICGaussSeidel; } tolerance 1e-12; relTol 0; maxIter 200; } ".*(rho|rhoFinal)" { solver diagonal; } p_rgh { solver GAMG; tolerance 1e-12; relTol 0.01; smoother DIC; } p_rghFinal { solver PCG; preconditioner { preconditioner GAMG; tolerance 1e-12; relTol 0; nVcycles 2; smoother DICGaussSeidel; nPreSweeps 2; } tolerance 1e-12; relTol 0; maxIter 20; } U { solver smoothSolver; smoother GaussSeidel; tolerance 1e-10; relTol 0; nSweeps 1; } "(T|k|B|nuTilda).*" { solver smoothSolver; smoother symGaussSeidel; tolerance 1e-10; relTol 0; } "(U|k|omega|s).*" { solver smoothSolver; smoother symGaussSeidel; nSweeps 1; tolerance 1e-10; relTol 0.1; }; } PIMPLE { momentumPredictor no; transonic no; nOuterCorrectors 1; nCorrectors 2; nNonOrthogonalCorrectors 0; } Code:
FoamFile { version 2.0; format ascii; class dictionary; location "system"; object fvSchemes; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // ddtSchemes { default Euler; // first order in time } gradSchemes { default Gauss linear; } divSchemes // Convection Schemes Settings { default none; div(phi,alpha) Gauss vanLeer; div(rhoPhi,U) Gauss linearUpwind grad(U); // UEqn div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear; // vanLeer; div(rhoPhi,T) Gauss upwind; // TEqn div(rhoPhi,p) Gauss linear; div(phi,p) Gauss linear; div(rhoPhi,K) Gauss linear; // TEqn div(phirb,alpha) Gauss interfaceCompression 1; // alphaEqn } laplacianSchemes { default Gauss linear corrected; } interpolationSchemes // interpolating cell-centred values to face values { default linear; } snGradSchemes { default corrected; } wallDist { method meshWave; } I believe that the problem is at my BC's. Are they making sense? Thank you! |
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July 10, 2020, 05:09 |
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#2 |
Member
Join Date: May 2016
Posts: 39
Rep Power: 10 |
Hi,
I think, based on my own experience, that this negative temperatures crashes are happening because of the algebraic numerical method calculating the interface. Basically the use of MULES and artificial compression. I would suggest using a geometric description of the interface (isoADVECTOR). The compressible solver compressibleInterIsoFoam was just released with the v2006 release. This should greately stabilize your simulations and hopefully avoid any further crashes (while improving your solution accuracy). Cheers. |
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July 11, 2020, 15:28 |
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#3 |
New Member
Robson Leo Pachaly
Join Date: Oct 2019
Posts: 3
Rep Power: 7 |
Thank you so much for your reply. I'm using the interIsoFoam and it is stable right now.
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June 22, 2022, 03:03 |
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#4 |
Member
Join Date: Nov 2020
Posts: 53
Rep Power: 6 |
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Tags |
compressible, compressibleinterfoam, multiphase, negative temperature, printstack |
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