volume fraction gradient

Gitesh P · November 7, 2012, 12:42

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

kmooney · November 8, 2012, 09:51

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!

Gitesh P · November 9, 2012, 03:14

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

duongquaphim · November 9, 2012, 09:42

instead of const volVectorField& gradAlpha = fvc::grad(alpha); use const volScalarField& gradAlpha = mag(fvc::grad(alpha));

Gitesh P · November 12, 2012, 08:04

Hello,

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

With regards,
GP

duongquaphim · November 12, 2012, 09:32

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

Gitesh P · November 13, 2012, 07:43

Hello again,

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

With regards,
GP

November 7, 2012, 12:42	volume fraction gradient	#1
Gitesh P Member Gitesh Join Date: Jan 2010 Location: Finland Posts: 73 Rep Power: 16	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

November 8, 2012, 09:51		#2
kmooney Senior Member Kyle Mooney Join Date: Jul 2009 Location: San Francisco, CA USA Posts: 323 Rep Power: 17	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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November 9, 2012, 03:14		#3
Gitesh P Member Gitesh Join Date: Jan 2010 Location: Finland Posts: 73 Rep Power: 16	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

November 9, 2012, 09:42		#4
duongquaphim Member Duong A. Hoang Join Date: Apr 2009 Location: Delft, Netherlands Posts: 93 Rep Power: 17	instead of const volVectorField& gradAlpha = fvc::grad(alpha); use const volScalarField& gradAlpha = mag(fvc::grad(alpha));

November 12, 2012, 08:04		#5
Gitesh P Member Gitesh Join Date: Jan 2010 Location: Finland Posts: 73 Rep Power: 16	Hello, Can you say me where I include/write this line? I mean in which directory/file. With regards, GP

November 12, 2012, 09:32		#6
duongquaphim Member Duong A. Hoang Join Date: Apr 2009 Location: Delft, Netherlands Posts: 93 Rep Power: 17	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

November 13, 2012, 07:43		#7
Gitesh P Member Gitesh Join Date: Jan 2010 Location: Finland Posts: 73 Rep Power: 16	Hello again, You mean I need to put these lines some where at the end in interFoam.C file ? With regards, GP