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/");
// 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();
}
}
// 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();
}
/// 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 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/");
IncomprFlowParam<T> parameters(
(T) 1e-2, // uMax
(T) 300., // Re
100, // N
5., // lx
1. // ly
);
const T logT = (T)0.02;
const T imSave = (T)0.1;
const T vtkSave = (T)3.;
const T maxT = (T)10.1;
writeLogFile(parameters, "Poiseuille flow");
MultiBlockLattice2D<T, DESCRIPTOR> lattice (
parameters.getNx(), parameters.getNy(),
new BGKdynamics<T,DESCRIPTOR>(parameters.getOmega()) );
lattice.periodicity().toggle(0, false);
OnLatticeBoundaryCondition2D<T,DESCRIPTOR>*
//boundaryCondition = createInterpBoundaryCondition2D<T,DESCRIPTOR>();
boundaryCondition = createLocalBoundaryCondition2D<T,DESCRIPTOR>();
defineCylinderGeometry(lattice, parameters);
setupInletAndBulk(lattice, parameters, *boundaryCondition);
//copyUnknownOnOutlet(lattice, parameters, *boundaryCondition);
velocityNeumannOutlet(lattice, parameters, *boundaryCondition);
lattice.initialize();
// Main loop over time iterations.
for (plint iT=0; iT*parameters.getDeltaT()<maxT; ++iT) {
if ((iT+1)%parameters.nStep(logT)==0) {
pcout << computeAverageDensity(lattice) << endl;
pcout << computeAverageEnergy(lattice) << endl;
}
if (iT%parameters.nStep(logT)==0) {
pcout << "step " << iT
<< "; lattice time=" << lattice.getTimeCounter().getTime()
<< "; t=" << iT*parameters.getDeltaT()
<< "; av energy="
<< setprecision(10) << getStoredAverageEnergy<T>(lattice)
<< "; av rho="
<< getStoredAverageDensity<T>(lattice) << endl;
}
if (iT%parameters.nStep(imSave)==0) {
pcout << "Saving Gif ..." << endl;
writeGifs(lattice, iT);
}
if (iT%parameters.nStep(vtkSave)==0 && iT>0) {
pcout << "Saving VTK file ..." << endl;
writeVTK(lattice, parameters, iT);
}
// Lattice Boltzmann iteration step.
lattice.collideAndStream();
}
delete boundaryCondition;
}