CFD Online Discussion Forums - Adding line source term for scalar transport by fvOptions

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Adding line source term for scalar transport by fvOptions

Hi,

I have been trying to add a line source on the ground for scalar transport by fvOptions. My idea is to approximate the line source by a narrow area source. So I extract a faceSet from the lowerWall (the ground boundary) as follows:

Code:

actions

(

    {

        name    f0; //http://openfoamwiki.net/index.php/TopoSet

        type    faceSet;

        action  new;

        source  patchToFace;

        sourceInfo

        {

            name lowerWall; 

        }

    }

    {

        name    f0;

        type    faceSet;  //2D

        action  subset;

        source  boxToFace;

        sourceInfo

        {

             boxes ((1.1076 0 0.4)(1.122 0 1.6)   (1.158 0 0.4)(1.1724 0 1.6));

        }

    }

);

And then I set the source strength in the fvOptions dictionary as follows:

Code:

scalarTracer //name

    {

        type            scalarSemiImplicitSource;

        active          true;

        selectionMode   all;  // all, cellSet, points, cellZone  

        cellSet       f0;//TSsourceCells; 

        

        scalarSemiImplicitSourceCoeffs

        {

            volumeMode      specific; // absolute <quantity>; specific <quantity>/m^3

            injectionRateSuSp 

            {

                TS      (0.2936 0); //kg/m^3/s  0.01/0.0340557 

            }

        }

    }

My code runs well, but there is some important thing that confuses me:
My total source strength is 0.01 kg/s, the area of f0 is 0.0340557 m^2. Is it right to set TS as 0.01/0.0340557 with the volumeMode being 'specific' ?

By the way, if there is better ideas for a line source term, please tell me too.

Thank you!
Wayne

Re:Adding line source term for scalar transport by fvOptions

Dear wayne14,
I have the same problem, Have sresolved the your's? Please I need help
Kader

Quote:

Originally Posted by AbdelkaderDZ (Post 572593)

Dear wayne14,
I have the same problem, Have sresolved the your's? Please I need help
Kader

Hi Korichi Abdelkader,

Yes, I have solved the problem.
But I need a little time to explain what I do, just let you know I will answer it.

Best wishes,
Yan Wang

The idea mentioned in my previous post is somewhat strange, the more comfortable way to implement a line source (or whatever shape) is to have a suitable mesh, which matches exactly (or approximately) with the shape of your source term.

Here I will give three steps for the problem:

1. Pay attention to the source shape when you generate the mesh. Make the mesh matches with your source term.
2. Use topoSetDict to 'mark' all the cells the belong to your source term. Here is what I do:

Code:

actions

(



    {

        name    f0;

        type    cellSet;  

        action  new;

        source  boxToCell;

        sourceInfo

        {

          box (0.29286 -0.06 0)(0.30714 -0.057 0.03);

        }

    }

   {

        name    f0;

        type    cellZoneSet;

        action  new;

        source  setToCellZone;

        sourceInfo

        {

            set f0;           // name of the cellSet

        }

    }

);

3. Use fvOptions to set the intensity of your source term, like the following:

Code:

FoamFile

{

    version     2.0;

    format      ascii;

    class       dictionary;

    location    "system";

    object      fvOptions;

}

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

    scalarTracer //name

    {

        type            scalarSemiImplicitSource;

        active          true;

        selectionMode   cellZone;  // all, cellSet, points, cellZone 

        cellZone       f0;//sourceCells; 

        

        scalarSemiImplicitSourceCoeffs

        {

            volumeMode      absolute; // absolute <quantity>; specific <quantity>/m^3

            injectionRateSuSp 

            {

                TS      (10 0); //kg/s  

            }

        }

    }

Hope it helpful,

Regards,
Yan Wang

Re:Adding line source term for scalar transport by fvOptions

Thank you Yan,
I will try it.
Kader

Re:Adding line source term for scalar transport by fvOptions

Hi Yan,
I have tried, I have error when excuting topset, I have 0 point new.
Thanks

Quote:

Originally Posted by AbdelkaderDZ (Post 572633)

Hi Yan,
I have tried, I have error when excuting topset, I have 0 point new.
Thanks

Hi Kader,

Hope I am not having your name wrong.

When using topoSet, It's very important to make sure that the sourceInfo has been specified correctly.

For the below example, the centroid of all the cells belonging to the source term are within the 'box' region specified by vertex coordinates. Otherwise, no new cellZone will be generated.

Code:

  sourceInfo

        {

          box (0.29286 -0.06 0)(0.30714 -0.057 0.03);

        }

By the way, posting your error information may be helpful:)

Regards,
Yan Wang

Re:Adding line source term for scalar transport by fvOptions

Quote:

Originally Posted by wayne14 (Post 572617)

Code:

TS (10 0); //kg/s

I would like to ask does the scalar transport have unit kg/s?