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volume fraction gradient

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Old   November 7, 2012, 13:42
Default volume fraction gradient
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Gitesh
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Hello,

Can any one suggest how to get the volume fraction gradient to calculate interfacial area ?

I mean if I have a dispersed phase volume fraction 'alpha'. And I want to calculate the '|grad(alpha)|' field then how I can get the values in OF/paraFoam ?

With regards,
GP
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Old   November 8, 2012, 10:51
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Kyle Mooney
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If you want to be able to see the alpha gradient field during post processing something like this might work for you:

Code:
if(runTime.write())
{
    const volVectorField& gradAlpha = fvc::grad(alpha);
    gradAlpha.write();
}
Cheers!
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Old   November 9, 2012, 04:14
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Hello,

Thank you for that.

Yes now I am able to get the gradients of alpha.

How about absolute value of it. I mean I need to calculate absolute value of gradient of alpha.

Is there any utility where I can direct find those values ?

With regards,
GP
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Old   November 9, 2012, 10:42
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instead of const volVectorField& gradAlpha = fvc::grad(alpha); use const volScalarField& gradAlpha = mag(fvc::grad(alpha));
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Old   November 12, 2012, 09:04
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Hello,

Can you say me where I include/write this line? I mean in which directory/file.

With regards,
GP
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Old   November 12, 2012, 10:32
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you can just put the above code in interFoam.C for instance and compile. The outputs should be exported into time folders in the same way of U, p or alpha1 fields.

Duong
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Old   November 13, 2012, 08:43
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Hello again,

You mean I need to put these lines some where at the end in interFoam.C file ?

With regards,
GP
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