C++ MultiBlockLattice2D类代码示例

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

    MultiBlockLattice2D<T, DESCRIPTOR> lattice (
           nx, ny, new BGKdynamics<T,DESCRIPTOR>(omega) );

    lattice.periodicity().toggleAll(true); // Set periodic boundaries.

    defineInitialDensityAtCenter(lattice);

    // First part: loop over time iterations.
    for (plint iT=0; iT<maxIter; ++iT) {
        lattice.collideAndStream();
    }

    // Second part: Data analysis.
    Array<T,2> velocity;
    lattice.get(nx/2, ny/2).computeVelocity(velocity);
    pcout << "Velocity in the middle of the lattice: ("
          << velocity[0] << "," << velocity[1] << ")" << endl;

    pcout << "Velocity norm along a horizontal line: " << endl;
    Box2D line(0, 100, ny/2, ny/2);
    pcout << setprecision(3) << *computeVelocityNorm(*extractSubDomain(lattice, line)) << endl;

    plb_ofstream ofile("profile.dat");
    ofile << setprecision(3) << *computeVelocityNorm(*extractSubDomain(lattice, line)) << endl;

    pcout << "Average density in the domain: " << computeAverageDensity(lattice) << endl;
    pcout << "Average energy in the domain: " << computeAverageEnergy(lattice) << endl;
}

void halfCircleSetup (
        MultiBlockLattice2D<T,DESCRIPTOR>& lattice, plint N, plint radius,
        OnLatticeBoundaryCondition2D<T,DESCRIPTOR>& boundaryCondition )
{
    // The channel is pressure-driven, with a difference deltaRho
    //   between inlet and outlet.
    T deltaRho = 1.e-2;
    T rhoIn  = 1. + deltaRho/2.;
    T rhoOut = 1. - deltaRho/2.;

    Box2D inlet (0,     N/2, N/2, N/2);
    Box2D outlet(N/2+1, N,   N/2, N/2);

    boundaryCondition.addPressureBoundary1P(inlet, lattice);
    boundaryCondition.addPressureBoundary1P(outlet, lattice);

    // Specify the inlet and outlet density.
    setBoundaryDensity (lattice, inlet, rhoIn);
    setBoundaryDensity (lattice, outlet, rhoOut);

    // Create the initial condition.
    Array<T,2> zeroVelocity((T)0.,(T)0.);
    T constantDensity = (T)1;
    initializeAtEquilibrium (
       lattice, lattice.getBoundingBox(), constantDensity, zeroVelocity );

    defineDynamics(lattice, lattice.getBoundingBox(),
                   new BounceBackNodes<T>(N, radius),
                   new BounceBack<T,DESCRIPTOR>);

    lattice.initialize();
}

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

    IncomprFlowParam<T> parameters (
        (T) 1e-2,  // uMax
        (T) 10.,   // Re
        30,        // N
        2.,        // lx
        1.         // ly 
    );

    plint nx = parameters.getNx();
    plint ny = parameters.getNy();

    writeLogFile(parameters, "Poiseuille flow");

    MultiBlockLattice2D<T, DESCRIPTOR> lattice (
              nx, ny,
              new BGKdynamics<T,DESCRIPTOR>(parameters.getOmega()) );
    OnLatticeBoundaryCondition2D<T,DESCRIPTOR>*
        boundaryCondition = createLocalBoundaryCondition2D<T,DESCRIPTOR>();
    createPoiseuilleBoundaries(lattice, parameters, *boundaryCondition);
    lattice.initialize();

    // The following command opens a text-file, in which the velocity-profile
    // in the middle of the channel will be written and several successive
    // time steps. Note the use of plb_ofstream instead of the standard C++
    // ofstream, which is required to guarantee a consistent behavior in MPI-
    // parallel programs.
    plb_ofstream successiveProfiles("velocityProfiles.dat");

    // Main loop over time steps.
    for (plint iT=0; iT<10000; ++iT) {
        if (iT%1000==0) {
            pcout << "At iteration step " << iT
                  << ", the density along the channel is " << endl;
            pcout << setprecision(7)
                  << *computeDensity(lattice, Box2D(0, nx-1, ny/2, ny/2))
                  << endl << endl;

            Box2D profileSection(nx/2, nx/2, 0, ny-1);
            successiveProfiles
                << setprecision(4)
                  // (2) Convert from lattice to physical units.
                << *multiply (
                       parameters.getDeltaX() / parameters.getDeltaT(),
                  // (1) Compute velocity norm along the chosen section.
                       *computeVelocityNorm (lattice, profileSection) )
                << endl;

        }

        // Lattice Boltzmann iteration step.
        lattice.collideAndStream();
    }

    delete boundaryCondition;
}

int main(int argc, char* argv[]) {
    plbInit(&argc, &argv);

    global::directories().setOutputDir("./tmp/");

    IncomprFlowParam<T> parameters(
        (T) 1e-2,  // uMax
        (T) 100.,  // Re
        64,        // N
        5.,        // lx
        1.         // ly
    );
    const T logT     = (T)0.01;
    const T imSave   = (T)0.02;
    const T maxT     = (T)1.1;

    writeLogFile(parameters, "Poiseuille flow");

    MultiBlockLattice2D<T, DESCRIPTOR> lattice (
        parameters.getNx(), parameters.getNy(),
        new BGKdynamics<T,DESCRIPTOR>(parameters.getOmega()) );

    OnLatticeBoundaryCondition2D<T,DESCRIPTOR>*
    boundaryCondition = createLocalBoundaryCondition2D<T,DESCRIPTOR>();

    cylinderSetup(lattice, parameters, *boundaryCondition);

    // Main loop over time iterations.
    for (plint iT=0; iT*parameters.getDeltaT()<maxT; ++iT) {
        // At this point, the state of the lattice corresponds to the
        //   discrete time iT. However, the stored averages (getStoredAverageEnergy
        //   and getStoredAverageEnergy) correspond to the previous time iT-1.

        if (iT%parameters.nStep(imSave)==0) {
            pcout << "Saving Gif ..." << endl;
            writeGifs(lattice, iT);
        }

        if (iT%parameters.nStep(logT)==0) {
            pcout << "step " << iT
                  << "; t=" << iT*parameters.getDeltaT();
        }

        // Lattice Boltzmann iteration step.
        lattice.collideAndStream();

        // At this point, the state of the lattice corresponds to the
        //   discrete time iT+1, and the stored averages are upgraded to time iT.
        if (iT%parameters.nStep(logT)==0) {
            pcout << "; av energy ="
                  << setprecision(10) << getStoredAverageEnergy<T>(lattice)
                  << "; av rho ="
                  << getStoredAverageDensity<T>(lattice) << endl;
        }
    }
    delete boundaryCondition;
}

int main(int argc, char* argv[]) {
    plbInit(&argc, &argv);

    global::directories().setOutputDir("./tmp/");

    // Parameters of the simulation
    plint N         = 400;    // Use a 400x200 domain.
    plint maxT      = 20001;
    plint imageIter = 1000;
    T omega        = 1.;
    plint radius    = N/3;    // Inner radius of the half-circle.

    // Parameters for the creation of the multi-block.
    
    // d is the width of the block which is exempted from the full domain.
    plint d = (plint) (2.*std::sqrt((T)util::sqr(radius)-(T)util::sqr(N/4.)));
    plint x0 = (N-d)/2 + 1;  // Begin of the exempted block.
    plint x1 = (N+d)/2 - 1;  // End of the exempted block.

    // Create a block distribution with the three added blocks.
    plint envelopeWidth = 1;
    SparseBlockStructure2D sparseBlock(N+1, N/2+1);
    sparseBlock.addBlock(Box2D(0, x0,      0, N/2),   sparseBlock.nextIncrementalId());
    sparseBlock.addBlock(Box2D(x0+1, x1-1, 0, N/4+1), sparseBlock.nextIncrementalId());
    sparseBlock.addBlock(Box2D(x1, N,      0, N/2),   sparseBlock.nextIncrementalId());

    // Instantiate the multi-block, based on the created block distribution and
    // on default parameters.
    MultiBlockLattice2D<T, DESCRIPTOR> lattice (
        MultiBlockManagement2D (
            sparseBlock,
            defaultMultiBlockPolicy2D().getThreadAttribution(), envelopeWidth ),
        defaultMultiBlockPolicy2D().getBlockCommunicator(),
        defaultMultiBlockPolicy2D().getCombinedStatistics(),
        defaultMultiBlockPolicy2D().getMultiCellAccess<T,DESCRIPTOR>(),
        new BGKdynamics<T,DESCRIPTOR>(omega)
    );

    pcout << getMultiBlockInfo(lattice) << std::endl;

    OnLatticeBoundaryCondition2D<T,DESCRIPTOR>*
        boundaryCondition = createLocalBoundaryCondition2D<T,DESCRIPTOR>();

    halfCircleSetup(lattice, N, radius, *boundaryCondition);

    // Main loop over time iterations.
    for (plint iT=0; iT<maxT; ++iT) {
        if (iT%imageIter==0) {
            pcout << "Saving Gif at time step " << iT << endl;
            writeGifs(lattice, iT);
        }
        lattice.collideAndStream();
    }

    delete boundaryCondition;
}

// Initialize the lattice at zero velocity and constant density, except
//   for a slight density excess on a square sub-domain.
void defineInitialDensityAtCenter(MultiBlockLattice2D<T,DESCRIPTOR>& lattice)
{
    // Initialize constant density everywhere.
    initializeAtEquilibrium (
           lattice, lattice.getBoundingBox(), rho0, u0 );

    // And slightly higher density in the central box.
    initializeAtEquilibrium (
           lattice, lattice.getBoundingBox(), initializeRhoOnCircle );

    lattice.initialize();
}

void createBoundariesFromVelocityField(MultiBlockLattice2D<T,DESCRIPTOR>& lattice,
                                       MultiTensorField2D<T,2>& velocity)
{
    applyProcessingFunctional( new BoundaryFromVelocityFunctional2D<T,DESCRIPTOR>,
                               lattice.getBoundingBox(),
                               lattice, velocity );
}

/// A functional, used to instantiate bounce-back nodes at the locations of the cylinder
void cylinderSetup( MultiBlockLattice2D<T,DESCRIPTOR>& lattice,
                    IncomprFlowParam<T> const& parameters,
                    OnLatticeBoundaryCondition2D<T,DESCRIPTOR>& boundaryCondition )
{
    const plint nx = parameters.getNx();
    const plint ny = parameters.getNy();

    Box2D outlet(nx-1,nx-1, 1,ny-2);

    // Create Velocity boundary conditions everywhere
    boundaryCondition.setVelocityConditionOnBlockBoundaries (
        lattice, Box2D(0, nx-1, 0, 0) );
    boundaryCondition.setVelocityConditionOnBlockBoundaries (
        lattice, Box2D(0, nx-1, ny-1, ny-1) );
    boundaryCondition.setVelocityConditionOnBlockBoundaries (
        lattice, Box2D(0,0, 1,ny-2) );
    // .. except on right boundary, where we prefer a fixed-pressure condition.
    boundaryCondition.setPressureConditionOnBlockBoundaries (
        lattice, outlet );

    setBoundaryVelocity (
        lattice, lattice.getBoundingBox(),
        PoiseuilleVelocity<T>(parameters) );
    setBoundaryDensity (
        lattice, outlet,
        ConstantDensity<T>(1.) );
    initializeAtEquilibrium (
        lattice, lattice.getBoundingBox(),
        PoiseuilleVelocityAndDensity<T,DESCRIPTOR>(parameters) );

    plint cx = nx/4;
    plint cy = ny/2+2;
    plint r  = cy/4;
    DotList2D cylinderShape;
    for (plint iX=0; iX<nx; ++iX) {
        for (plint iY=0; iY<ny; ++iY) {
            if ( (iX-cx)*(iX-cx) + (iY-cy)*(iY-cy) < r*r ) {
                cylinderShape.addDot(Dot2D(iX,iY));
            }
        }
    }
    defineDynamics(lattice, cylinderShape, new BounceBack<T,DESCRIPTOR>);

    lattice.initialize();
}

/*
void writeGif(MultiBlockLattice2D<PlbT,DESCRIPTOR>& lattice, plint iter)
{
    ImageWriter<PlbT> imageWriter("leeloo");
    imageWriter.writeScaledGif(createFileName("u", iter, 6),
                               *computeVelocityNorm(lattice) );
}
*/
void writeVTK(MultiBlockLattice2D<PlbT,DESCRIPTOR>& lattice,
              IncomprFlowParam<PlbT> const& parameters, plint iter)
{
    T dx = parameters.getDeltaX();
    T dt = parameters.getDeltaT();
    VtkImageOutput2D<T> vtkOut(createFileName("vtk", iter, 6), dx);
    vtkOut.writeData<T>(*realPart<PlbT,T>(*computeVelocityNorm(lattice),lattice.getBoundingBox()), "velocityNorm", dx/dt);
    //vtkOut.writeData<2,T>(*computeVelocity(lattice), "velocity", dx/dt);
}

void cavitySetup( MultiBlockLattice2D<T,DESCRIPTOR>& lattice,
                  IncomprFlowParam<T> const& parameters,
                  OnLatticeBoundaryCondition2D<T,DESCRIPTOR>& boundaryCondition )
{
    const plint nx = parameters.getNx();
    const plint ny = parameters.getNy();

    boundaryCondition.setVelocityConditionOnBlockBoundaries(lattice);

    setBoundaryVelocity(lattice, lattice.getBoundingBox(), Array<T,2>(0.,0.) );
    initializeAtEquilibrium(lattice, lattice.getBoundingBox(), 1., Array<T,2>(0.,0.) );

    T u = parameters.getLatticeU();
    setBoundaryVelocity(lattice, Box2D(1, nx-2, ny-1, ny-1), Array<T,2>(u,0.) );
    initializeAtEquilibrium(lattice, Box2D(1, nx-2, ny-1, ny-1), 1., Array<T,2>(u,0.) );

    lattice.initialize();
}

/// A functional, used to instantiate bounce-back nodes at the locations of the cylinder
void cylinderSetup( MultiBlockLattice2D<PlbT,DESCRIPTOR>& lattice,
                    IncomprFlowParam<PlbT> const& parameters,
                    OnLatticeBoundaryCondition2D<PlbT,DESCRIPTOR>& boundaryCondition )
{
    const plint nx = parameters.getNx();
    const plint ny = parameters.getNy();
    Box2D outlet(nx-1,nx-1, 1, ny-2);

    // Create Velocity boundary conditions everywhere
    boundaryCondition.setVelocityConditionOnBlockBoundaries (
            lattice, Box2D(0, 0, 1, ny-2) );
    boundaryCondition.setVelocityConditionOnBlockBoundaries (
            lattice, Box2D(0, nx-1, 0, 0) );
    boundaryCondition.setVelocityConditionOnBlockBoundaries (
            lattice, Box2D(0, nx-1, ny-1, ny-1) );
    // .. except on right boundary, where we prefer an outflow condition
    //    (zero velocity-gradient).
    boundaryCondition.setVelocityConditionOnBlockBoundaries (
            lattice, Box2D(nx-1, nx-1, 1, ny-2), boundary::outflow );

    setBoundaryVelocity (
            lattice, lattice.getBoundingBox(),
            PoiseuilleVelocity<PlbT>(parameters) );
    setBoundaryDensity (
            lattice, outlet,
            ConstantDensity<PlbT>(1.) );
    initializeAtEquilibrium (
            lattice, lattice.getBoundingBox(),
            PoiseuilleVelocityAndDensity<PlbT>(parameters) );

    plint cx     = nx/4;
    plint cy     = ny/2+2; // cy is slightly offset to avoid full symmetry,
                          //   and to get a Von Karman Vortex street.
    plint radius = cy/4;
    defineDynamics(lattice, lattice.getBoundingBox(),
                   new CylinderShapeDomain2D<T>(cx,cy,radius),
                   new plb::BounceBack<PlbT,DESCRIPTOR>);

    lattice.initialize();
}

void channelSetup( MultiBlockLattice2D<T,NSDESCRIPTOR>& lattice,
                   IncomprFlowParam<T> const& parameters,
                   OnLatticeBoundaryCondition2D<T,NSDESCRIPTOR>& boundaryCondition,
                   T alpha, T frequency, T amplitude)
{
    const plint nx = parameters.getNx();
    const plint ny = parameters.getNy();

    Box2D bottom(   0,nx-1,   0,   0);
    Box2D top(   0,nx-1,   ny-1,   ny-1);

    boundaryCondition.addVelocityBoundary1N(bottom, lattice);
    boundaryCondition.addPressureBoundary1P(top,    lattice);

    Array<T,2> u((T)0.,(T)0.);
    setBoundaryVelocity( lattice, lattice.getBoundingBox(), u );
    initializeAtEquilibrium(lattice,lattice.getBoundingBox(),(T)1.0,u);

    Array<T,NSDESCRIPTOR<T>::d> force(womersleyForce((T)0, amplitude, frequency, parameters),0.);
    setExternalVector(lattice,lattice.getBoundingBox(),NSDESCRIPTOR<T>::ExternalField::forceBeginsAt,force);

    lattice.initialize();
}

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

    // For the choice of the parameters G, rho0, and psi0, we refer to the book
    //   Michael C. Sukop and Daniel T. Thorne (2006), 
    //   Lattice Boltzmann Modeling; an Introduction for Geoscientists and Engineers.
    //   Springer-Verlag Berlin/Heidelberg.
    
    const T omega = 1.0;
    const int nx   = 400;
    const int ny   = 400;
    const T G      = -120.0;
    const int maxIter  = 100001;
    const int saveIter = 100;
    const int statIter = 100;
    
    const T rho0 = 200.0;
    const T deltaRho = 1.0;
    const T psi0 = 4.0;

    MultiBlockLattice2D<T, DESCRIPTOR> lattice (
            nx,ny, new ExternalMomentBGKdynamics<T, DESCRIPTOR>(omega) );
            
    lattice.periodicity().toggleAll(true);

    // Use a random initial condition, to activate the phase separation.
    applyProcessingFunctional(new RandomInitializer<T,DESCRIPTOR>(rho0,deltaRho), 
                              lattice.getBoundingBox(),lattice);

    // Add the data processor which implements the Shan/Chen interaction potential.
    plint processorLevel = 1;
    integrateProcessingFunctional (
            new ShanChenSingleComponentProcessor2D<T,DESCRIPTOR> (
                G, new interparticlePotential::PsiShanChen94<T>(psi0,rho0) ),
            lattice.getBoundingBox(), lattice, processorLevel );

    lattice.initialize();
    
    pcout << "Starting simulation" << endl;
    for (int iT=0; iT<maxIter; ++iT) {
        if (iT%statIter==0) {
            auto_ptr<MultiScalarField2D<T> > rho( computeDensity(lattice) );
            pcout << iT << ": Average rho fluid one = " << computeAverage(*rho) << endl;
            pcout << "Minimum density: " << computeMin(*rho) << endl;
            pcout << "Maximum density: " << computeMax(*rho) << endl;
        }
        if (iT%saveIter == 0) {
            ImageWriter<T>("leeloo").writeScaledGif (
                    createFileName("rho", iT, 6), *computeDensity(lattice) );
        }

        lattice.collideAndStream();
    }
}

void setupInletAndBulk( MultiBlockLattice2D<T,DESCRIPTOR>& lattice,
                        IncomprFlowParam<T> const& parameters,
                        OnLatticeBoundaryCondition2D<T,DESCRIPTOR>& boundaryCondition )
{
    const plint ny = parameters.getNy();

    // Create Velocity boundary conditions on inlet
    boundaryCondition.addVelocityBoundary0N(Box2D(   0,   0,   0,ny-1), lattice);

    setBoundaryVelocity (
            lattice, Box2D(   0,   0,   0,ny-1),
            PoiseuilleVelocity<T>(parameters) );
    initializeAtEquilibrium (
            lattice, lattice.getBoundingBox(),
            PoiseuilleVelocityAndDensity<T,DESCRIPTOR>(parameters) );
}

T computeRMSerror ( MultiBlockLattice2D<T,NSDESCRIPTOR>& lattice,
                    IncomprFlowParam<T> const& parameters,
                    T alpha, plint iT, bool createImage=false)
{
    MultiTensorField2D<T,2> analyticalVelocity(lattice);
    setToFunction( analyticalVelocity, analyticalVelocity.getBoundingBox(),
                   WomersleyVelocity<T>(parameters,alpha,(T)iT) );
    MultiTensorField2D<T,2> numericalVelocity(lattice);
    computeVelocity(lattice, numericalVelocity, lattice.getBoundingBox());

    // Divide by lattice velocity to normalize the error
    return 1./parameters.getLatticeU() *
           // Compute RMS difference between analytical and numerical solution
           std::sqrt( computeAverage( *computeNormSqr (
                                          *subtract(analyticalVelocity, numericalVelocity)
                                      ) ) );
}