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what is the sigma12/sigma13 in interMixingFoam?

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Old   May 26, 2014, 07:32
Default what is the sigma12/sigma13 in interMixingFoam?
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I want to know the meaning of the sigma12/sigma13 in openMixingfoam/constant/transportproperties.

many thx.
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Old   May 26, 2014, 10:30
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Greetings Wais,

I'm going to have to ask you a few existential questions:
  1. What case are you talking about? I can't find any example case on the Internet named "openMixingfoam".
  2. Which OpenFOAM version are you using?
Best regards,
Bruno
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Old   May 26, 2014, 10:46
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Quote:
Originally Posted by wyldckat View Post
Greetings Wais,

I'm going to have to ask you a few existential questions:
  1. What case are you talking about? I can't find any example case on the Internet named "openMixingfoam".
  2. Which OpenFOAM version are you using?
Best regards,
Bruno
Sorry,it's interMixingfoam, and I use 2.3.0
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Old   May 26, 2014, 13:08
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Ah, OK. I've corrected the thread title.

In the tutorial "multiphase/interMixingFoam/laminar/damBreak" it says this:
Quote:
Originally Posted by constant/transportProperties
Code:
// Surface tension coefficients
sigma12           sigma12 [1 0 -2 0 0 0 0] 0.05;
sigma13           sigma13 [1 0 -2 0 0 0 0] 0.04;
My first guess would be that these were the tension coefficients between X and Y and X and Z... but I'm probably wrong here.

In this file: https://github.com/OpenFOAM/OpenFOAM...ceProperties.H - the description is this:
Quote:
Code:
        //- Surface tension 1-2
        dimensionedScalar sigma12_;

        //- Surface tension 1-3
        dimensionedScalar sigma13_;
On the same file is later on this:
Quote:
Code:
        tmp<volScalarField> sigma() const
        {
            volScalarField limitedAlpha2(max(mixture_.alpha2(), scalar(0)));
            volScalarField limitedAlpha3(max(mixture_.alpha3(), scalar(0)));

            return
                (limitedAlpha2*sigma12_ + limitedAlpha3*sigma13_)
               /(limitedAlpha2 + limitedAlpha3 + SMALL);
        }
Therefore, "sigma12" is for the surface tension between the phase 1 and phase 2, while "sigma13" is for the surface tension between the phase 1 and phase 3.

As to what the surface tension is... it should be be explained in papers and CFD documents related to multiphase

Best regards,
Bruno
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