bstep2d.cpp

open lattice boltzmann project www.openlb.org

/*  This file is part of the OpenLB library
 *
 *  Copyright (C) 2006, 2007 Jonas Latt
 *  Address: Rue General Dufour 24,  1211 Geneva 4, Switzerland 
 *  E-mail: [e-mail]
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public 
 *  License along with this program; if not, write to the Free 
 *  Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 *  Boston, MA  02110-1301, USA.
*/

#include "olb2D.h"
#ifndef OLB_PRECOMPILED // Unless precompiled version is used,
  #include "olb2D.hh"   // include full template code
#endif
#include <vector>
#include <cmath>
#include <iostream>
#include <fstream>

using namespace olb;
using namespace olb::descriptors;
using namespace olb::graphics;
using namespace std;

typedef double T;
#define DESCRIPTOR D2Q9Descriptor

T poiseuilleVelocity(int iY, int N, T u) {
    T y = (T)iY / (T)N;
    return 4.*u * (y-y*y);
}

void iniGeometry( BlockStructure2D<T,DESCRIPTOR>& lattice,
                  LBunits<T> const& converter,
                  Dynamics<T, DESCRIPTOR>& bulkDynamics,
                  OnLatticeBoundaryCondition2D<T,DESCRIPTOR>& boundaryCondition )
{
    const T lx1   = 5.0;
    const T ly1   = 0.75;
    const T omega = converter.getOmega();

    const int nx = converter.getNx();
    const int ny = converter.getNy();
    const int nx1 = converter.nCell(lx1);
    const int ny1 = converter.nCell(ly1);

    lattice.defineDynamics(0,nx-1,0,ny-1,   &bulkDynamics);
    lattice.defineDynamics(0,nx1-1,0,ny1-1, &instances::getNoDynamics<T,DESCRIPTOR>());

    boundaryCondition.addVelocityBoundary0N(0,0,        ny1+1,ny-2, omega);
    boundaryCondition.addVelocityBoundary0N(nx1,nx1,    1,ny1-1, omega);
    boundaryCondition.addVelocityBoundary0P(nx-1,nx-1,  1, ny-2, omega);
    boundaryCondition.addVelocityBoundary1P(1,nx-2,     ny-1,ny-1, omega);
    boundaryCondition.addVelocityBoundary1N(1,nx1-1,    ny1,ny1, omega);
    boundaryCondition.addVelocityBoundary1N(nx1+1,nx-2, 0,0, omega);

    boundaryCondition.addExternalVelocityCornerNN(0,ny1, omega);
    boundaryCondition.addExternalVelocityCornerNN(nx1,0, omega);

    boundaryCondition.addExternalVelocityCornerNP(0,ny-1, omega);
    boundaryCondition.addExternalVelocityCornerPN(nx-1,0, omega);
    boundaryCondition.addExternalVelocityCornerPP(nx-1,ny-1, omega);

    boundaryCondition.addInternalVelocityCornerNN(nx1,ny1, omega);

    for (int iX=0; iX<=nx1; ++iX) {
        for (int iY=ny1; iY<ny; ++iY) {
            T vel[] = {
                poiseuilleVelocity(iY-ny1, ny-ny1-1, converter.getLatticeU()),
                T()
            };
            lattice.get(iX,iY).defineRhoU((T)1, vel);
            lattice.get(iX,iY).iniEquilibrium((T)1, vel);
        }
    }

    for (int iX=nx1+1; iX<nx; ++iX) {
        for (int iY=0; iY<ny; ++iY) {
            T vel[] = {
                poiseuilleVelocity( iY, ny-1,
                                    converter.getLatticeU()*((T)1-(T)ny1/(T)ny) ),
                T()
            };
            lattice.get(iX,iY).defineRhoU((T)1, vel);
            lattice.get(iX,iY).iniEquilibrium((T)1, vel);
        }
    }

    lattice.initialize();
}

void writeGifs(BlockStructure2D<T,DESCRIPTOR>& lattice,
               LBunits<T> const& converter, int iter)
{
    const int imSize = 600;
    DataAnalysisBase2D<T,DESCRIPTOR> const& analysis = lattice.getDataAnalysis();
    ImageWriter<T> imageWriter("leeloo");
    imageWriter.writeScaledGif(createFileName("u5_", iter, 6),
                               analysis.getVelocityNorm(), imSize,imSize);
    imageWriter.writeScaledGif(createFileName("omega", iter, 6),
                               analysis.getVorticity(), imSize,imSize);
}

int main(int argc, char* argv[]) {
    olbInit(&argc, &argv);
    singleton::directories().setOutputDir("./tmp/");

    LBunits<T> converter(
            (T) 2e-2,  // uMax
            (T) 500.,  // Re
            60,        // N
            20.,       // lx
            1.5        // ly
    );
    writeLogFile(converter, "2D Backward facing step");

    const T maxT        = (T)10.;
    const int  iterStat = 100;
    const int  iterGif  = 2000;
    const int  iterSave = 10000;

#ifndef PARALLEL_MODE_MPI  // sequential program execution
    BlockLattice2D<T, DESCRIPTOR> lattice(converter.getNx(), converter.getNy() );
#else                      // parallel program execution
    MultiBlockLattice2D<T, DESCRIPTOR> lattice (
        createRegularDataDistribution( converter.getNx(), converter.getNy() ) );
#endif

    ConstRhoBGKdynamics<T, DESCRIPTOR> bulkDynamics (
                      converter.getOmega(),
                      instances::getBulkMomenta<T,DESCRIPTOR>()
    );

    // choose between local and non-local boundary condition
    OnLatticeBoundaryCondition2D<T,DESCRIPTOR>*
        // boundaryCondition = createInterpBoundaryCondition2D(lattice);
        boundaryCondition = createLocalBoundaryCondition2D(lattice);

    iniGeometry(lattice, converter, bulkDynamics, *boundaryCondition);

    for (int iT=0; iT*converter.getDeltaT()<maxT; ++iT) {
        if (iT%iterStat==0) {
            cout << "step " << iT
                 << "; t=" << iT*converter.getDeltaT()
                 << "; av energy="
                 << lattice.getStatistics().getAverageEnergy()
                 << "; av rho="
                 << lattice.getStatistics().getAverageRho() << endl;
        }
        if (iT%iterGif==0 && iT>0) {
            writeGifs(lattice, converter, iT);
        }
        if (iT%iterSave==0 && iT>0) {
            cout << "Checkpointing the system at t=" << iT << endl;
            saveData(lattice, "bstep2d.checkpoint");
            // The data can be reloaded using
            //     loadData(lattice, "bstep2d.checkpoint");
        }

        lattice.collideAndStream();
    }

    delete boundaryCondition;
}