CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Post-Processing

Macro existing for calculating a cell surface?

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   June 10, 2010, 15:50
Post Macro existing for calculating a cell surface?
  #1
New Member
 
Join Date: Jun 2010
Posts: 14
Rep Power: 6
maximeg is on a distinguished road
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
maximeg is offline   Reply With Quote

Old   June 11, 2010, 03:32
Default
  #2
Senior Member
 
Mark Olesen
Join Date: Mar 2009
Location: http://olesenm.github.io/
Posts: 774
Rep Power: 17
olesen will become famous soon enough
Quote:
Originally Posted by maximeg View Post
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.
olesen is offline   Reply With Quote

Old   June 14, 2010, 11:49
Default
  #3
New Member
 
Join Date: Jun 2010
Posts: 14
Rep Power: 6
maximeg is on a distinguished road
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:imensionedField <double, Foam::volMesh>::<anonymous>.Foam::Field<double>::< anonymous>.Foam::List<double>::<anonymous>.Foam::U List<T>:perator[] [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
maximeg is offline   Reply With Quote

Old   June 14, 2010, 15:49
Default
  #4
New Member
 
Join Date: Jun 2010
Posts: 14
Rep Power: 6
maximeg is on a distinguished road
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:

Code:
#include "calc.H"
#include "fvc.H"

void Foam::calc(const argList& args, const Time& runTime, const fvMesh& mesh)
{

    volScalarField magVorticity        // Imports the results of the vortex vorticity
    (                    
        IOobject            
        (                
            "magVorticity",        
            runTime.timeName(),        
            mesh,            
            IOobject::MUST_READ,    
            IOobject::AUTO_WRITE    
        ),                
        mesh                
    );      

    scalar circulation = 0.0;
    scalar r = 0.0;
    const volScalarField& magSf = mesh.magSf();

    forAll(magVorticity, cellI)
    {

        if (distance < r[cellI])        // If the radius (distance) stays lower than the critical radius (r)...
        {
            circulation += magSf.magVorticity[cellI];     // ...calculation of the circulation.
        }

    }

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

Code:
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:89: error: invalid types ‘Foam::scalar[Foam::label]’ for array subscript
MaxVorCirc.C:94: error: ‘magSf’ was not declared in this scope
make: *** [Make/linux64GccDPOpt/MaxVorCirc.o] Error 1
Any help would be very appreciated.

Thank you in advance!

Maxime
maximeg is offline   Reply With Quote

Old   June 15, 2010, 02:23
Default
  #5
Senior Member
 
Mark Olesen
Join Date: Mar 2009
Location: http://olesenm.github.io/
Posts: 774
Rep Power: 17
olesen will become famous soon enough
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.
olesen is offline   Reply With Quote

Old   June 17, 2010, 18:04
Default
  #6
New Member
 
Join Date: Jun 2010
Posts: 14
Rep Power: 6
maximeg is on a distinguished road
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
maximeg is offline   Reply With Quote

Old   July 13, 2010, 07:37
Default
  #7
New Member
 
Join Date: Jun 2010
Posts: 1
Rep Power: 0
AlterSchwede is on a distinguished road
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
AlterSchwede is offline   Reply With Quote

Old   July 13, 2010, 13:30
Default
  #8
New Member
 
Join Date: Jun 2010
Posts: 14
Rep Power: 6
maximeg is on a distinguished road
Quote:
Originally Posted by AlterSchwede View Post
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
maximeg is offline   Reply With Quote

Reply

Tags
cell

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
boundaries with gmshToFoam‏ ouafa Open Source Meshers: Gmsh, Netgen, CGNS, ... 7 May 21, 2010 12:43
Cell ID macro ?!?!?!?!?! bohis FLUENT 1 November 14, 2008 08:26
UDF macro for surface tension coefficient Frederik FLUENT 2 May 30, 2005 10:54
Macro for velocity on the face of the cell Dragos FLUENT 0 April 7, 2005 11:12
cell to cell relation CMB CD-adapco 1 December 4, 2003 04:05


All times are GMT -4. The time now is 01:38.