CFD Online Discussion Forums - Calculating flow rate across a section

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Calculating flow rate across a section

Hi all Foamers,

I've search about how to calculate fields in different parts of my case and I've a doubt about what is better (or maybe the unique way) for calculating the flow across a section of my study case.

The case is a tank with pipe (to simplify) where the fluid flows. Which of these two post-processing at run-time you recommend to my case?
1) fieldValue
2) probes

Maybe there are other options, if any better, please tell me.

Thanks in advance,

Eric

Code:

/*--------------------------------*- C++ -*----------------------------------*\

| =========                 |                                                 |

| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |

|  \\    /   O peration     | Version:  2.2.0                                 |

|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |

|    \\/     M anipulation  |                                                 |

\*---------------------------------------------------------------------------*/

FoamFile

{

    version     2.0;

    format      ascii;

    class       dictionary;

    object      sampleDict;

}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

setFormat raw;

surfaceFormat vtk;



formatOptions

{

    ensight

    {

        format  ascii;

    }

}

interpolationScheme cell;



fields

(

    alpha1

    phi

    

);



surfaces

(

  triangleCut

    {

        // Cutingplane using iso surface

        type            cuttingPlane;

        planeType       pointAndNormal;

        pointAndNormalDict

        {

            basePoint       (0.0 1.0 1.54);

            normalVector    (0.0 0.866025 0.5);

        }

        interpolate     true;

        }

)

If I ran it separately (first alpha1 and then phi) it works for alpha1 but not for phi. I've tried all types of interpolationscheme I found in the dict info but I don't know if there are more not included there.

Any help?

Quote:

Originally Posted by edalmau (Post 436512)

I found out that I can use sample to save info across a plane.

I've my SampleDict here but it doesn't work for phi. I read in other posts that it may depend on the interpolation scheme and what kind of "variable" are you trying to store. Phi is defined as SurfaceScalarField.

This leads me to 2 questions:
1) Which kind of interpolation can work with phi assuming I've a plane or cut plane defined?
2) Is there any way to sample an operation between two variables? In my case I need alpha1*phi.

If I ran it separately (first alpha1 and then phi) it works for alpha1 but not for phi. I've tried all types of interpolationscheme I found in the dict info but I don't know if there are more not included there.

Any help?

I personally use swak4Foam in that kind of situation. It allows me to evaluate whatever combination of fields I want

Ok thanks I'll take a look on that app. I've look around other posts and for sampling only 1 component of the U vector is there any way to type that? Cause in one post I found "U.component(i)" where i is the component number from 0-2 but it doesn't work for me. The sample app is making only the cutting plane file but not filled with U data only geometrical.