# Explanation of sinusoidal heat source code on fvOptions

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 June 24, 2022, 02:12 Explanation of sinusoidal heat source code on fvOptions #1 New Member   Giulia Join Date: Feb 2022 Posts: 19 Rep Power: 4 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!! saidc. likes this.

 June 24, 2022, 03:22 #2 Member   Join Date: Jan 2022 Location: Germany Posts: 72 Rep Power: 4 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) letoppina likes this.

June 24, 2022, 03:27
#3
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Giulia
Join Date: Feb 2022
Posts: 19
Rep Power: 4
Quote:
 Originally Posted by überschwupper 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)
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?

 June 24, 2022, 04:09 #4 Member   Join Date: Jan 2022 Location: Germany Posts: 72 Rep Power: 4 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.

 Tags chtmultiregionfoam, fvoptions, heat source, regions, sinusoidal

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