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Explanation of sinusoidal heat source code on fvOptions

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Old   June 24, 2022, 02:12
Default Explanation of sinusoidal heat source code on fvOptions
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Giulia
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Hello,



I am using OpenFoam version 6 and chtMultiRegionFoam as a solver to simulate a solid body (heat source) exchanging heat with a moving fluid. In order to give a sinusoidal variation of the heat source, I am using fvOptions on the solid region with the following code:



Code:
    energySource
    {
        type            scalarCodedSource;
        active          yes;
        timeStart       0;
        duration        1e6;
        name            sourceTime; 
    selectionMode   all;

    scalarCodedSourceCoeffs
        {
        selectionMode   all; 
                volumeMode      specific;           
        fields          (h);
            codeInclude
            #{
            #};

            codeCorrect
            #{
                Pout<< "**codeCorrect**" << endl;
            #};

            codeAddSup
            #{
                    const Time& time = mesh().time();
                    const scalarField& V = mesh_.V();
                    const vectorField& C = mesh_.C();
                    scalarField& heSource = eqn.source();

            heSource += 2.729e6*sin(2*3.14*0.1*time.value())*V;  

                Pout << "***codeAddSup***" << endl;
            #};

            codeSetValue
            #{
                Pout<< "**codeSetValue**" << endl;
            #};

            // Dummy entry. Make dependent on above to trigger recompilation
               code
            #{
                    $codeInclude
                    $codeCorrect
                    $codeAddSup
                    $codeSetValue
            #};
        }
My code is properly working but I have some questions:



- what does "const scalarField& V = mesh_.V()" mean?

- what does "const vectorField& C = mesh_.C()" mean?

- why heSource has to be multiplied by V?

- what is a dummy entry?



Any further explication about the code is highly appreciated.



Thank you very much for your help!!
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Old   June 24, 2022, 03:22
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Code:
const scalarField& V = mesh_.V()
const vectorField& C = mesh_.C()

Both are just const references to the cell volume of each cell or cell centers.


Why the heat source is multiplied with V depends on the formulation of the source term. I would guess that the relation derived is normed by the volume and in order get the correct values/dimensions it is multiplied by it.


I dont know the reason or the idea behind a dummy entry. But there are #-symbols has to do with preprocessor directives and inside the directory are the directories defined in your file (for example $AddSup)
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Old   June 24, 2022, 03:27
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Giulia
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Quote:
Originally Posted by überschwupper View Post
Code:
const scalarField& V = mesh_.V()
const vectorField& C = mesh_.C()

Both are just const references to the cell volume of each cell or cell centers.


Why the heat source is multiplied with V depends on the formulation of the source term. I would guess that the relation derived is normed by the volume and in order get the correct values/dimensions it is multiplied by it.


I dont know the reason or the idea behind a dummy entry. But there are #-symbols has to do with preprocessor directives and inside the directory are the directories defined in your file (for example $AddSup)
Thank you for your reply!
So this means that if I want to give a heat source not dependent on the volume (so an absolute heat source expressed in W and not W/m3) I just have to remove the multiplication of V?
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Old   June 24, 2022, 04:09
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I cant give you the exact answer to this, because I dont know the exact definiton of your source term. Thats why I mentioned my guess. But it would be the other way as you have written.



Do yoou know the dimensions of the prefactor 2.729e6? Dimensioncontrol could help you here.
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chtmultiregionfoam, fvoptions, heat source, regions, sinusoidal

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