Macro existing for calculating a cell surface?
 

Hi everyone!

I'm a starter at openFOAM and I'd like to calculate the circulation around a 2D vortex (the simulation is done and I already have the coordinates of the point of maximum vorticity (<=> vortex center)).

To do so, I need to integrate the surface of cells in order to get a disc surrounding the vortex, and then sum up the product of each cell surface by the vorticity to get the final circulation:
"gamma(circulation)=sum(wi(vorticity at cell i) x Ai(surface of cell i))"

Is there a macro already existing allowing you to calculate the surface of each cell? I didn't find anything on the forum concerning that.
I would like to avoid doing something like that:
CellSurface(i)=[y(i+1)-y(i)].[x(i+1)-x(i)]

Thanks in advance for you're help!

Maxime

In the fvMesh class
http://foam.sourceforge.net/doc/Doxy...1_1fvMesh.html

the Sf() and magSf() methods can be used to get the surface vector and the magnitude of the surface vector for the mesh faces, respectively.

the inherited cells() method
http://foam.sourceforge.net/doc/Doxy...h-members.html

allows you to find the faces corresponding to each cell.

Hi!
Here's the code for the calculation of the circulation, I'm really having a hard time finding out why it doesn't work:

// * * * * * * * * * * * * * * * * * *Circulation calculation (beginning)* * * * * * * * * * * * * * * * * * * * * * * * //

scalar circulation = 0.0;
scalar r = 0.0;
//scalar cell_area = 0.0;
const surfaceScalarField& magSf = mesh.magSf();

forAll(magVorticity, cellI)
{
//cell_area = (mesh.C()[cellI+1].component(0)-mesh.C()[cellI].component(0)).(mesh.C()[cellI+1].component(1)-mesh.C()[cellI].component(1)); // Surface of one cell

if (distance < r[cellI]) // If the radius stays inferior to r_c...
{
// circulation = circulation + magVorticity[cellI].cell_area[cellI]; // ...calculation of the circulation

circulation = circulation + magVorticity[cellI].magSf[cellI];
}

}

// * * * * * * * * * * * * * * * * * *Circulation calculation (end)* * * * * * * * * * * * * * * * * * * * * * * * //

The message given in the terminal is as follows (after I did wmake):

make: Warning: File `linux64GccDPOpt/options' has modification time 6e+02 s in the future
make: warning: Clock skew detected. Your build may be incomplete.
make: Warning: File `Make/linux64GccDPOpt/dontIncludeDeps' has modification time 6e+02 s in the future
Making dependency list for source file MaxVorCirc.C
make: warning: Clock skew detected. Your build may be incomplete.
make: Warning: File `MaxVorCirc.dep' has modification time 6e+02 s in the future
SOURCE=MaxVorCirc.C ; g++ -m64 -Dlinux64 -DWM_DP -Wall -Wno-strict-aliasing -Wextra -Wno-unused-parameter -Wold-style-cast -Wnon-virtual-dtor -O3 -DNoRepository -ftemplate-depth-40 -I/usr/local/OpenFOAM/OpenFOAM-1.6/src/postProcessing/postCalc -I/usr/local/OpenFOAM/OpenFOAM-1.6/src/finiteVolume/lnInclude -IlnInclude -I. -I/usr/local/OpenFOAM/OpenFOAM-1.6/src/OpenFOAM/lnInclude -I/usr/local/OpenFOAM/OpenFOAM-1.6/src/OSspecific/POSIX/lnInclude -fPIC -c $SOURCE -o Make/linux64GccDPOpt/MaxVorCirc.o
MaxVorCirc.C: In function ‘void Foam::calc(const Foam::argList&, const Foam::Time&, const Foam::fvMesh&)’:
MaxVorCirc.C:86: error: invalid types ‘Foam::scalar[Foam::label]’ for array subscript
MaxVorCirc.C:93: error: request for member ‘magSf’ in ‘magVorticity.Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>::<anonymous>.Foam::DimensionedField <double, Foam::volMesh>::<anonymous>.Foam::Field<double>::< anonymous>.Foam::List<double>::<anonymous>.Foam::U List<T>::operator[] [with T = double](cellI)’, which is of non-class type ‘double’
MaxVorCirc.C:80: warning: unused variable ‘magSf’
make: *** [Make/linux64GccDPOpt/MaxVorCirc.o] Error 1

Any help given would be very appreciated.
Thanking you in advance,
Maxime

Just to make it a little bit more clear (updated version also):

I have to calculate the circulation in a vortex. My code is as follows:

The error message I get in the terminal is as follows:

Any help would be very appreciated.

Thank you in advance!

Maxime

Please re-read my previous post. You are, for example, trying to use a surfaceScalarField (which is defined for mesh faces) for cells, and lots of other dubious things.

Hello,
I'd like to know how I can access/choose the area (of only one of the 6 faces) of a internal cubical finite volume (not near a patch).
I know I have to use the magSf command, but I don't know which face area (or which direction) of the finite volume it gives me.
Thank you.
Maxime

Hey maximeg,

Have you solved your problem in order to calculate the circulation? In my simulation (flow around around a car) I need to calculate the circulation as well, but here for rectangular "boxes" around the car.

Can you help me out with some advice?

Thanks in advance,

\AlterSchwede

Hi!
No, unfortunately I didn't find what I was looking for. I calculated the surface manually instead (not hard but not general). I don't think you'll be able to do that though (in my case, all the cells have the same size).
If you find anything please let me know.
Maxime