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 Andrea_85 January 24, 2013 12:27

High diffusion in interFoam

Hi all,

i am simulating a meniscus that moves in capillary tubes of different shape with small contact angle (from 1° up to 30°). I have observed a very large diffusion of the interface which sometimes leads to non-physical or not-expected results. I was wondering if i can limit diffusion without without touching cAlpha, which is set to 1 at the moment, maybe playing with schemes for convective terms. Which schemes can be used in interFoam to limit diffusion?

This is how my fvScheme looks like:
Code:

```ddtSchemes {     default        Euler; } gradSchemes {     default        leastSquares; //    grad(U)        Gauss linear; //    grad(alpha1)    Gauss linear; } divSchemes {     div(rho*phi,U)  Gauss limitedLinearV 1;     div(phi,alpha)  Gauss vanLeer;     div(phirb,alpha) Gauss interfaceCompression; } laplacianSchemes {     default        Gauss linear corrected; } interpolationSchemes {     default        linear; } snGradSchemes {     default        corrected; } fluxRequired {     default        no;     p_rgh;     pcorr;     alpha1; }```
and fvSolution

Code:

```solvers {     pcorr     {         solver          PCG;         preconditioner  DIC;         tolerance      1e-10;         relTol          0;     }     p_rgh     {         solver          PCG;         preconditioner  DIC;         tolerance      1e-07;         relTol          0.05;     }     p_rghFinal     {         solver          PCG;         preconditioner  DIC;         tolerance      1e-07;         relTol          0;     }     U     {         solver          PBiCG;         preconditioner  DILU;         tolerance      1e-06;         relTol          0;     }     UFinal     {         solver          PBiCG;         preconditioner  DILU;         tolerance      1e-06;         relTol          0;     } PIMPLE {     momentumPredictor yes;     nCorrectors    3;     nNonOrthogonalCorrectors 1;     nAlphaCorr      1;     nAlphaSubCycles 3;     cAlpha          1; }```
and controlDict

Code:

```application    interFoam; startFrom      startTime; startTime      0; stopAt          endTime; endTime        0.22; deltaT          0.000000001; writeControl    adjustableRunTime; writeInterval  0.01; purgeWrite      0; writeFormat    ascii; writePrecision  6; writeCompression uncompressed; timeFormat      general; timePrecision  6; runTimeModifiable yes; adjustTimeStep  yes; maxCo          0.1; maxAlphaCo      0.1; maxDeltaT      0.01;```
thanks

andrea

 akidess January 24, 2013 16:59

Instead of vanLeer you can use MULES or SuperBee, both of which should be more compressive. Don't expect too much though.

 Andrea_85 January 31, 2013 05:08

Thanks Anton, i'll give them a try.

best

andrea

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