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Abnormal velocity when modelling wall boiling using reactingTwoPhaseEulerFoam |
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#1 |
New Member
Zhao
Join Date: Dec 2019
Posts: 4
Rep Power: 6 ![]() |
Hi Foamers,
I am modelling water-vapour wall boiling inside a vertical pipe, using a wedge asymmetric mesh. The length is 2m, with 15.4 mm diameter. Pipe wall heat flux is 570000w.m-2 and the average velocity at the inlet is 1m.s-1, working at 45 bar pressure. Turbulence model for both phases is k-epsilon. The simulation runs good at the beginning, but when the vapour volume fraction be closing to 0.1 the max velocity increases rapidly to around 3m.s-1, and then the volume fraction as well. For reference, I have attached some files here. If my question is unclear, please let me know in the comment. Regards, Zao Liquid velocity code: Code:
/*--------------------------------*- C++ -*----------------------------------*\ ========= | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox \\ / O peration | Website: https://openfoam.org \\ / A nd | Version: 7 \\/ M anipulation | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volVectorField; location "0"; object U.liquid; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 1 -1 0 0 0 0]; internalField uniform (0 0 1); boundaryField { inlet { type mapped; field U.liquid; setAverage 1; average (0 0 1); interpolationScheme cell; value uniform (0 0 1); } outlet { type pressureInletOutletVelocity; phi phi.liquid; value uniform (0 0 1); } wall { type noSlip; } front { type wedge; } back { type wedge; } } // ************************************************************************* // alphat.liquid code: Code:
/*--------------------------------*- C++ -*----------------------------------*\ ========= | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox \\ / O peration | Website: https://openfoam.org \\ / A nd | Version: 7 \\/ M anipulation | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volScalarField; location "0"; object alphat.liquid; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [1 -1 -1 0 0 0 0]; internalField uniform 1e-8; boundaryField { inlet { type calculated; value uniform 1e-8; } outlet { type calculated; value uniform 1e-8; } wall { type compressible::alphatWallBoilingWallFunction; otherPhase gas; phaseType liquid; Prt 0.85; /*Cmu 0.09; kappa 0.41; E 9.8; relax 0.01; dmdt uniform 0;*/ partitioningModel { type Lavieville; alphaCrit 0.2; } nucleationSiteModel { type LemmertChawla; } departureDiamModel { type TolubinskiKostanchuk; } departureFreqModel { type Cole; } value uniform 0.01; } front { type wedge; } back { type wedge; } } // ************************************************************************* // |
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#2 |
New Member
Zhao
Join Date: Dec 2019
Posts: 4
Rep Power: 6 ![]() |
Reason found.
mu coefficients is supposed to be corrected as: Code:
transport { muCoeffs<8> (0.0004282 -6.19667e-7 0 0 0 0 0 0); kappaCoeffs<8> (1.14518355 -0.001017 0 0 0 0 0 0); } |
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#3 |
New Member
Tolu
Join Date: Feb 2020
Posts: 1
Rep Power: 0 ![]() |
where did you get the coefficients from
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Tags |
reactingtwophaseeulerfoam, wall boiling |
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