CalcDivergence.cpp

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/**
 * This function calculate the divergence starting from an .fld file.
 * It is meant to be used with solutions produced by the
 * incompressible Navier-Stokes solver.  To use it with solutions
 * coming form another solver further generalisations are required.
 */
#include <cstdio>
#include <cstdlib>

#include <MultiRegions/ExpList.h>
#include <MultiRegions/ExpList1D.h>
#include <MultiRegions/ExpList2D.h>
#include <MultiRegions/ExpList3D.h>
#include <MultiRegions/ExpList2DHomogeneous1D.h>
#include <MultiRegions/ExpList3DHomogeneous1D.h>
#include <MultiRegions/ExpList3DHomogeneous2D.h>

using namespace Nektar;

int main(int argc, char *argv[])
{
    int i,j;

    if(argc != 3)
    {
        fprintf(stderr,"Usage: ./CalcDivergence file.xml file.fld\n");
        exit(1);
    }

    LibUtilities::SessionReaderSharedPtr vSession
            = LibUtilities::SessionReader::CreateInstance(argc, argv);


    //----------------------------------------------
    // Read in mesh from input file
    string meshfile(argv[argc-2]);
    SpatialDomains::MeshGraphSharedPtr graphShPt = SpatialDomains::MeshGraph::Read(vSession);//meshfile);
    //----------------------------------------------

    //----------------------------------------------
    // Import field file.
    string fieldfile(argv[argc-1]);
    vector<LibUtilities::FieldDefinitionsSharedPtr> fielddef;
    vector<vector<NekDouble> > fielddata;
    LibUtilities::Import(fieldfile,fielddef,fielddata);
    bool useFFT = false;
    bool dealiasing = false;
    //----------------------------------------------

    //----------------------------------------------
    // Define Expansion
    int expdim  = graphShPt->GetMeshDimension();
    int nfields = fielddef[0]->m_fields.size();

    Array<OneD, MultiRegions::ExpListSharedPtr> Exp(nfields + 1);
    
    switch(expdim)
    {
    case 1:
        {
            ASSERTL0(fielddef[0]->m_numHomogeneousDir <= 2,"Quasi-3D approach is only set up for 1 or 2 homogeneous directions");
            
            if(fielddef[0]->m_numHomogeneousDir == 1)
            {
                MultiRegions::ExpList2DHomogeneous1DSharedPtr Exp2DH1;
                
                // Define Homogeneous expansion
                //int nplanes = fielddef[0]->m_numModes[1];
                
                int nplanes; 
                vSession->LoadParameter("HomModesZ",nplanes,fielddef[0]->m_numModes[1]);
                
                // choose points to be at evenly spaced points at
                const LibUtilities::PointsKey Pkey(nplanes+1,LibUtilities::ePolyEvenlySpaced);
                const LibUtilities::BasisKey  Bkey(fielddef[0]->m_basis[1],nplanes,Pkey);
                NekDouble ly = fielddef[0]->m_homogeneousLengths[0];
                
                Exp2DH1 = MemoryManager<MultiRegions::ExpList2DHomogeneous1D>::AllocateSharedPtr(vSession,Bkey,ly,useFFT,dealiasing,graphShPt);
                Exp[0] = Exp2DH1;

                for(i = 1; i < nfields + 1; ++i)
                {
                    Exp[i] = MemoryManager<MultiRegions::ExpList2DHomogeneous1D>::AllocateSharedPtr(*Exp2DH1);
                }
            }
            else if(fielddef[0]->m_numHomogeneousDir == 2)
            {
                MultiRegions::ExpList3DHomogeneous2DSharedPtr Exp3DH2;
        
                // Define Homogeneous expansion
                //int nylines = fielddef[0]->m_numModes[1];
                //int nzlines = fielddef[0]->m_numModes[2];
                
                int nylines;
                int nzlines;
                vSession->LoadParameter("HomModesY",nylines,fielddef[0]->m_numModes[1]);
                vSession->LoadParameter("HomModesZ",nzlines,fielddef[0]->m_numModes[2]);
                
                // choose points to be at evenly spaced points at
                const LibUtilities::PointsKey PkeyY(nylines+1,LibUtilities::ePolyEvenlySpaced);
                const LibUtilities::BasisKey  BkeyY(fielddef[0]->m_basis[1],nylines,PkeyY);
                
                const LibUtilities::PointsKey PkeyZ(nzlines+1,LibUtilities::ePolyEvenlySpaced);
                const LibUtilities::BasisKey  BkeyZ(fielddef[0]->m_basis[2],nzlines,PkeyZ);
                
                NekDouble ly = fielddef[0]->m_homogeneousLengths[0];
                NekDouble lz = fielddef[0]->m_homogeneousLengths[1];
        
                Exp3DH2 = MemoryManager<MultiRegions::ExpList3DHomogeneous2D>::AllocateSharedPtr(vSession,BkeyY,BkeyZ,ly,lz,useFFT,dealiasing,graphShPt);
                Exp[0] = Exp3DH2;
        
                for(i = 1; i < nfields + 1; ++i)
                {
                    Exp[i] = MemoryManager<MultiRegions::ExpList3DHomogeneous2D>::AllocateSharedPtr(*Exp3DH2);
                }
            }
            else
            {
                MultiRegions::ExpList1DSharedPtr Exp1D;
                Exp1D = MemoryManager<MultiRegions::ExpList1D>
                    ::AllocateSharedPtr(vSession,graphShPt);
                Exp[0] = Exp1D;
                for(i = 1; i < nfields + 1; ++i)
                {
                    Exp[i] = MemoryManager<MultiRegions::ExpList1D>
                        ::AllocateSharedPtr(*Exp1D);
                }
            }
        }
        break;
    case 2:
        {
            ASSERTL0(fielddef[0]->m_numHomogeneousDir <= 1,"NumHomogeneousDir is only set up for 1");

            if(fielddef[0]->m_numHomogeneousDir == 1)
            {
                MultiRegions::ExpList3DHomogeneous1DSharedPtr Exp3DH1;

                // Define Homogeneous expansion
                //int nplanes = fielddef[0]->m_numModes[2];
                
                int nplanes; 
                vSession->LoadParameter("HomModesZ",nplanes,fielddef[0]->m_numModes[2]);
                
                // choose points to be at evenly spaced points at
                // nplanes + 1 points
                const LibUtilities::PointsKey Pkey(nplanes+1,LibUtilities::ePolyEvenlySpaced);
                const LibUtilities::BasisKey  Bkey(fielddef[0]->m_basis[2],nplanes,Pkey);
                NekDouble lz = fielddef[0]->m_homogeneousLengths[0];

                Exp3DH1 = MemoryManager<MultiRegions::ExpList3DHomogeneous1D>::AllocateSharedPtr(vSession,Bkey,lz,useFFT,dealiasing,graphShPt);
                Exp[0] = Exp3DH1;

                for(i = 1; i < nfields + 1; ++i)
                {
                    Exp[i] = MemoryManager<MultiRegions::ExpList3DHomogeneous1D>::AllocateSharedPtr(*Exp3DH1);
                }
            }
            else
            {
                MultiRegions::ExpList2DSharedPtr Exp2D;
                Exp2D = MemoryManager<MultiRegions::ExpList2D>
                    ::AllocateSharedPtr(vSession,graphShPt);
                Exp[0] =  Exp2D;
                
                for(i = 1; i < nfields + 1; ++i)
                {
                    Exp[i] = MemoryManager<MultiRegions::ExpList2D>
                        ::AllocateSharedPtr(*Exp2D);
                }
            }
        }
        break;
    case 3:
        {
            MultiRegions::ExpList3DSharedPtr Exp3D;
            Exp3D = MemoryManager<MultiRegions::ExpList3D>
                ::AllocateSharedPtr(vSession,graphShPt);
            Exp[0] =  Exp3D;

            for(i = 1; i < nfields + 1; ++i)
            {
                Exp[i] = MemoryManager<MultiRegions::ExpList3D>
                    ::AllocateSharedPtr(*Exp3D);
            }
        }
        break;
    default:
        ASSERTL0(false,"Expansion dimension not recognised");
        break;
    }

    //----------------------------------------------
    // Copy data from field file
    for(j = 0; j < nfields; ++j)
    {
        for(unsigned int i = 0; i < fielddata.size(); ++i)
        {
            Exp[j]->ExtractDataToCoeffs(fielddef [i],
                                        fielddata[i],
                                        fielddef [i]->m_fields[j],
                                        Exp[j]->UpdateCoeffs());
        }
        Exp[j]->BwdTrans(Exp[j]->GetCoeffs(),Exp[j]->UpdatePhys());
    }
    //----------------------------------------------
    
    int nq = Exp[0]->GetNpoints();
    
    Array<OneD, NekDouble> Ux(nq);
    Array<OneD, NekDouble> Vy(nq);
    Array<OneD, NekDouble> Div(nq);  
    
    switch(expdim)
    {
    case 1:
        {
            if(fielddef[0]->m_numHomogeneousDir == 1)
            {
                ASSERTL0(false,"Not implemented yet");
            }
            else if(fielddef[0]->m_numHomogeneousDir == 2)
            {
                ASSERTL0(false,"Not implemented yet");                
            }
            else 
            {
                ASSERTL0(false,"Not implemented yet");
            }
        }
        break;
    case 2:
        {
            if(fielddef[0]->m_numHomogeneousDir == 1)
            {
                ASSERTL0(false,"Not implemented yet");
            }
            else 
            {
                Exp[0]->PhysDeriv(MultiRegions::DirCartesianMap[0],Exp[0]->GetPhys(),Ux);
                Exp[0]->PhysDeriv(MultiRegions::DirCartesianMap[1],Exp[1]->GetPhys(),Vy);
        
                Vmath::Vsub(nq,Ux,1,Vy,1,Div,1);
        
                Exp[3]->FwdTrans(Div,Exp[3]->UpdateCoeffs());
            }
        }
        break;
    case 3:
        {
            ASSERTL0(false,"Not implemented yet");
        }
        break;
    default:
        {
            ASSERTL0(false,"Expansion dimension not recognised");
        }
        break;
    }
    
    //-----------------------------------------------
    // Write solution to file with additional computed fields
    string   fldfilename(argv[2]);
    string   out = fldfilename.substr(0, fldfilename.find_last_of("."));
    string   endfile("_with_divergence.fld");
    out += endfile;
    std::vector<LibUtilities::FieldDefinitionsSharedPtr> FieldDef
                                                = Exp[0]->GetFieldDefinitions();
    std::vector<std::vector<NekDouble> > FieldData(FieldDef.size());

    for(j = 0; j < nfields + 1; ++j)
    {
        for(i = 0; i < FieldDef.size(); ++i)
        {
            if (j >= nfields)
            {
                FieldDef[i]->m_fields.push_back("Div");
            }
            else
            {
                FieldDef[i]->m_fields.push_back(fielddef[i]->m_fields[j]);
            }
            Exp[j]->AppendFieldData(FieldDef[i], FieldData[i]);
        }
    }
    LibUtilities::Write(out, FieldDef, FieldData);
    //-----------------------------------------------

    return 0;
}