godunovmethod.cpp

Go to the documentation of this file.

#include "godunovmethod.h"


GodunovMethod::GodunovMethod(OrthoMesh &mesh,Function3D &fInitU,const VecDouble &cPor,Function3D &fPrescribedU,FaceFluxFunction &flux, FixedValueCondition &fixedC,double CFL) 
  :LaxFriedrichsForSystem(mesh,fInitU,cPor,fPrescribedU,flux,fixedC,CFL)
{
  
}



void GodunovMethod::iterateN(unsigned nSteps, double dt)
{
  unsigned posCell,negCell;

  //We iterate the method along faces, so 
  //alloc the vectors to contain the solutions in neg
  //and pos cells of the faces.  Remeber that the solution
  //in a cell is vector with a value for each component
  static VecDouble  vBC(n_components),vFlux(n_components);
  static VecDoubleRef  vQPos(n_components),vQNeg(n_components);

  //For each time step
  for (unsigned count = 0; count < nSteps; count++)
  {
    //Get the face iterator and the number of faces.
    OrthoMesh::Cash_Face_It face = m_mesh.begin_cash_face();
    OrthoMesh::Cash_Face_It endf = m_mesh.end_cash_face();
    m_vbc.rewind();
    bool hasbc;
    //m_solAnt receives the solution in time tn since
    //m_sol will contain the solution in tn+1. 
    m_solAnt = m_sol;

    //For each face
    for (;face!=endf;face++)
    {
      face->getAdjCellIndices(negCell,posCell);
      //Get the values of the previous solution in the right and left of the face
      hasbc=this->getValuesOfTheFaceCells(m_mesh,m_vbc,m_solAnt,face->index(),negCell,posCell,vQNeg,vQPos);

      //printf("face %d : Values %g %g %g | %g %g %g\n",face->index(),vQNeg(0),vQNeg(1),vQNeg(2),vQPos(0),vQPos(1),vQPos(2));
      
      //Get the indices of the cells that contain the face.
      //If the face is at boundary, it has just one cell.
      //In this case the method getAdjCells() return posCell == negCell
      if (posCell == OrthoMesh::INVALID_INDEX)
        posCell=negCell;
      else if (negCell == OrthoMesh::INVALID_INDEX)
        negCell=posCell;
        


      double posPor = getPorosity()(posCell);
      double negPor = getPorosity()(negCell);
      double mPor = (posPor + negPor)/2.0;



      m_flux.exactFluxAtFace(vFlux,face,vQNeg,vQPos);

      
      //Now update the cell values component by component
      for (unsigned cmp=0;cmp<n_components;cmp++)
      {
        
        //See if the face has prescribed boundary condition BC      
        double flux;
        if (!hasbc)    
        {
          /*
            The face doesnt have boundary condition BC
            proceed to the usual computation of the flux
            to calculate the amount of the mass passed through
            the face and divide it by the cell volume
          */
          
          flux = dt*face->areaPerCellVol() * vFlux(cmp) - mPor*(vQPos(cmp)-vQNeg(cmp))/6.0;
        }
        else //the face has BC, so dont add the stability term
        {
          flux = dt*face->areaPerCellVol() * vFlux(cmp);
        }

      
      
        //printf("face %d = %g,Pos: %d,Neg %d, SwPos = %g,SwNeg = %g \n",faceIndex,flux,face->getPosCellIndex(),face->getNegCellIndex(),SwPos,SwNeg);
        if (face->hasPosCell())
          m_sol(posCell,cmp) +=  + flux/posPor;

        if (face->hasNegCell())
          m_sol(negCell,cmp) +=  - flux/negPor;
        
      } //end for each component
    } //end for each face


  } //end for each time step

 
}

---