[sisetrun]

Hello everybody,

I am write a little post-processing tool which writes out the cell volumes and the velocities in the cells for a specific region in the domain.

Since I am only interested in a small part of my domain, I define a distance from z_min to z_max in an so called CoordinatesDict in the constant directory. I want to write the data in a .dat file to proceed working with python.

At the moment the code looks like this...

// This file is based on OpenFOAM.
// Description
//    Write mesh cell volumes in volumes.dat file and velocity in
//    velocity.dat file in current folder.

#include "OFstream.H"
#include "argList.H"
#include "timeSelector.H"
#include "Time.H"
#include "fvMesh.H"
#include "vectorIOField.H"
#include "volFields.H"
#include "surfaceFields.H"


//#include "fvCFD.H"

using namespace Foam;

int main(int argc, char *argv[])
{
    timeSelector::addOptions();

#   include "setRootCase.H"
    
    Info << "\n***EXTRACT CELL VOLUMES AND VELOCITIES***\n" << endl; 
    Info << "This applications is extacting the volumes and the velocities from a region in the domain\n" << endl;
    
#   include "createTime.H"
    instantList timeDirs = timeSelector::select0(runTime, args);

#   include "createMesh.H"
#   include "createFields.H"


    Info << "1) Reading all volumes..." << endl;
    Info << "Extracting cells between z = " << z_min.value();
    Info << " and z = " << z_max.value() << endl;
    
    OFstream volumes("volumes_" + runTime.timeName() + ".dat");    

    forAll(mesh.C(), idx)
      {

        if (mesh.C()[idx].component(2) >= z_min.value())
            if (mesh.C()[idx].component(2) <= z_max.value())
                {
                    volumes << idx << ' ' << mesh.V()[idx] << ' ' << mesh.C()[idx] << endl;
                }
      }
      
    Info << "Volumes DONE...\n" << endl;

    Info << "2) Reading velocities...\n" << endl;

    forAll(timeDirs, timeI)
    {

        runTime.setTime(timeDirs[timeI], timeI);
        Info<< "Time = " << runTime.timeName() << endl;

        #include "createMesh.H"
        #include "createFields.H"

        OFstream velocity("velocity_" + runTime.timeName() + ".dat");

        Info << "Extracting cells between z = " << z_min.value();
        Info << " and z = " << z_max.value() << endl;

        //Extract the z component of the cell centers
        Info << "Writing data to the files velocity_" + runTime.timeName() + ".dat" << "\n" << endl;

        forAll(mesh.C(), idx)
        {

          if (mesh.C()[idx].component(2) >= z_min.value())

              if (mesh.C()[idx].component(2) <= z_max.value())
              {
                  velocity << idx << ' ' << U[idx].component(0) << ' ' <<  U[idx].component(1) << ' ' << U[idx].component(2) << endl;
              }
        }

    }

    Info << "Writing done \n" << endl;

    return 0;
}

My question: is there a way to skip the

#include "createMesh.H"
#include "createFields.H"

in the forAll(timeDirs, timeI)? When I leave out this statement, the program only writes out the velocities from the first time directory. Since I work with quite large meshes, reading the mesh for every time step is very time consuming.

I tried so come around with mesh.readUpdate() but I did not work out...

Thank a lot for your input!

Best regards