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Diffstat (limited to 'examples/multiComponent/youngLaplace2d/youngLaplace2d.cpp')
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diff --git a/examples/multiComponent/youngLaplace2d/youngLaplace2d.cpp b/examples/multiComponent/youngLaplace2d/youngLaplace2d.cpp new file mode 100644 index 0000000..698aa66 --- /dev/null +++ b/examples/multiComponent/youngLaplace2d/youngLaplace2d.cpp @@ -0,0 +1,315 @@ +/* Lattice Boltzmann sample, written in C++, using the OpenLB + * library + * + * Copyright (C) 2018 Robin Trunk + * E-mail contact: info@openlb.net + * The most recent release of OpenLB can be downloaded at + * <http://www.openlb.net/> + * + * 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. + */ + +/* youngLaplace2d.cpp + * In this example a Young-Laplace test is performed. A circular domain + * of fluid 2 is immersed in fluid 1. A diffusive interface forms and the + * surface tension can be calculated using the Laplace pressure relation. + * The pressure difference is calculated between a point in the middle of + * the circular domain and a point furthest away from it in the + * computational domain (here left bottom corner). + * + * This example shows the simplest case for the free-energy model with two + * fluid components. + */ + +#include "olb2D.h" +#include "olb2D.hh" // use only generic version! +#include <cstdlib> +#include <iostream> +#include <fstream> + +using namespace olb; +using namespace olb::descriptors; +using namespace olb::graphics; +using namespace std; + +typedef double T; +#define DESCRIPTOR D2Q9<CHEM_POTENTIAL,FORCE> + +// Parameters for the simulation setup +const int N = 100; +const T nx = 100.; +const T radius = 0.25 * nx; +const T alpha = 1.5; // Interfacial width [lattice units] +const T kappa1 = 0.0075; // For surface tensions [lattice units] +const T kappa2 = 0.005; // For surface tensions [lattice units] +const T gama = 1.; // For mobility of interface [lattice units] + +const int maxIter = 60000; +const int vtkIter = 200; +const int statIter = 1000; + + +void prepareGeometry( SuperGeometry2D<T>& superGeometry ) { + + OstreamManager clout( std::cout,"prepareGeometry" ); + clout << "Prepare Geometry ..." << std::endl; + + superGeometry.rename( 0,1 ); + + superGeometry.innerClean(); + superGeometry.checkForErrors(); + superGeometry.print(); + + clout << "Prepare Geometry ... OK" << std::endl; +} + + +void prepareLattice( SuperLattice2D<T, DESCRIPTOR>& sLattice1, + SuperLattice2D<T, DESCRIPTOR>& sLattice2, + Dynamics<T, DESCRIPTOR>& bulkDynamics1, + Dynamics<T, DESCRIPTOR>& bulkDynamics2, + UnitConverter<T, DESCRIPTOR>& converter, + SuperGeometry2D<T>& superGeometry ) { + + OstreamManager clout( std::cout,"prepareLattice" ); + clout << "Prepare Lattice ..." << std::endl; + + // define lattice Dynamics + sLattice1.defineDynamics( superGeometry, 0, &instances::getNoDynamics<T, DESCRIPTOR>() ); + sLattice2.defineDynamics( superGeometry, 0, &instances::getNoDynamics<T, DESCRIPTOR>() ); + + sLattice1.defineDynamics( superGeometry, 1, &bulkDynamics1 ); + sLattice2.defineDynamics( superGeometry, 1, &bulkDynamics2 ); + + // bulk initial conditions + // define circular domain for fluid 2 + std::vector<T> v( 2,T() ); + AnalyticalConst2D<T,T> zeroVelocity( v ); + + AnalyticalConst2D<T,T> one ( 1. ); + SmoothIndicatorCircle2D<T,T> circle( {nx/2., nx/2.}, radius, 10.*alpha ); + + AnalyticalIdentity2D<T,T> rho( one ); + AnalyticalIdentity2D<T,T> phi( one - circle - circle ); + + sLattice1.iniEquilibrium( superGeometry, 1, rho, zeroVelocity ); + sLattice2.iniEquilibrium( superGeometry, 1, phi, zeroVelocity ); + + sLattice1.initialize(); + sLattice2.initialize(); + + clout << "Prepare Lattice ... OK" << std::endl; +} + + +void prepareCoupling(SuperLattice2D<T, DESCRIPTOR>& sLattice1, + SuperLattice2D<T, DESCRIPTOR>& sLattice2) { + + OstreamManager clout( std::cout,"prepareCoupling" ); + clout << "Add lattice coupling" << endl; + + // Add the lattice couplings + // The chemical potential coupling must come before the force coupling + FreeEnergyChemicalPotentialGenerator2D<T, DESCRIPTOR> coupling1( + alpha, kappa1, kappa2); + FreeEnergyForceGenerator2D<T, DESCRIPTOR> coupling2; + + sLattice1.addLatticeCoupling( coupling1, sLattice2 ); + sLattice2.addLatticeCoupling( coupling2, sLattice1 ); + + clout << "Add lattice coupling ... OK!" << endl; +} + + +void getResults( SuperLattice2D<T, DESCRIPTOR>& sLattice2, + SuperLattice2D<T, DESCRIPTOR>& sLattice1, int iT, + SuperGeometry2D<T>& superGeometry, Timer<T>& timer, + UnitConverter<T, DESCRIPTOR> converter) { + + OstreamManager clout( std::cout,"getResults" ); + SuperVTMwriter2D<T> vtmWriter( "youngLaplace2d" ); + + if ( iT==0 ) { + // Writes the geometry, cuboid no. and rank no. as vti file for visualization + SuperLatticeGeometry2D<T, DESCRIPTOR> geometry( sLattice1, superGeometry ); + SuperLatticeCuboid2D<T, DESCRIPTOR> cuboid( sLattice1 ); + SuperLatticeRank2D<T, DESCRIPTOR> rank( sLattice1 ); + vtmWriter.write( geometry ); + vtmWriter.write( cuboid ); + vtmWriter.write( rank ); + vtmWriter.createMasterFile(); + } + + // Get statistics + if ( iT%statIter==0 ) { + // Timer console output + timer.update( iT ); + timer.printStep(); + sLattice1.getStatistics().print( iT, converter.getPhysTime(iT) ); + sLattice2.getStatistics().print( iT, converter.getPhysTime(iT) ); + } + + // Writes the VTK files + if ( iT%vtkIter==0 ) { + AnalyticalConst2D<T,T> half_( 0.5 ); + SuperLatticeFfromAnalyticalF2D<T, DESCRIPTOR> half(half_, sLattice1); + + SuperLatticeDensity2D<T, DESCRIPTOR> density1( sLattice1 ); + density1.getName() = "rho"; + SuperLatticeDensity2D<T, DESCRIPTOR> density2( sLattice2 ); + density2.getName() = "phi"; + + SuperIdentity2D<T,T> c1 (half*(density1+density2)); + c1.getName() = "density-fluid-1"; + SuperIdentity2D<T,T> c2 (half*(density1-density2)); + c2.getName() = "density-fluid-2"; + + vtmWriter.addFunctor( density1 ); + vtmWriter.addFunctor( density2 ); + vtmWriter.addFunctor( c1 ); + vtmWriter.addFunctor( c2 ); + vtmWriter.write( iT ); + + // calculate bulk pressure, pressure difference and surface tension + if(iT%statIter==0) { + AnalyticalConst2D<T,T> two_( 2. ); + AnalyticalConst2D<T,T> onefive_( 1.5 ); + AnalyticalConst2D<T,T> k1_( kappa1 ); + AnalyticalConst2D<T,T> k2_( kappa2 ); + AnalyticalConst2D<T,T> cs2_( 1./descriptors::invCs2<T,DESCRIPTOR>() ); + SuperLatticeFfromAnalyticalF2D<T, DESCRIPTOR> two(two_, sLattice1); + SuperLatticeFfromAnalyticalF2D<T, DESCRIPTOR> onefive(onefive_, sLattice1); + SuperLatticeFfromAnalyticalF2D<T, DESCRIPTOR> k1(k1_, sLattice1); + SuperLatticeFfromAnalyticalF2D<T, DESCRIPTOR> k2(k2_, sLattice1); + SuperLatticeFfromAnalyticalF2D<T, DESCRIPTOR> cs2(cs2_, sLattice1); + + // Calculation of bulk pressure: + // c_1 = density of fluid 1; c_2 = density of fluid 2 + // p_bulk = rho*c_s^2 + kappa1 * (3/2*c_1^4 - 2*c_1^3 + 0.5*c_1^2) + // + kappa2 * (3/2*c_2^4 - 2*c_2^3 + 0.5*c_2^2) + SuperIdentity2D<T,T> bulkPressure ( density1*cs2 + + k1*( onefive*c1*c1*c1*c1 - two*c1*c1*c1 + half*c1*c1 ) + + k2*( onefive*c2*c2*c2*c2 - two*c2*c2*c2 + half*c2*c2 ) ); + + AnalyticalFfromSuperF2D<T, T> interpolPressure( bulkPressure, true, 1); + double position[2] = { 0.5*nx, 0.5*nx }; + double pressureIn = 0.; + double pressureOut = 0.; + interpolPressure(&pressureIn, position); + position[0] = ((double)N/100.)*converter.getPhysDeltaX(); + position[1] = ((double)N/100.)*converter.getPhysDeltaX(); + interpolPressure(&pressureOut, position); + + clout << "Pressure Difference: " << pressureIn-pressureOut << " ; "; + clout << "Surface Tension: " << radius*(pressureIn-pressureOut) << std::endl; + clout << "Analytical Pressure Difference: " << alpha/(6.*radius) * (kappa1 + kappa2) << " ; "; + clout << "Analytical Surface Tension: " << alpha/6. * (kappa1 + kappa2) << std::endl; + } + } +} + + +int main( int argc, char *argv[] ) { + + // === 1st Step: Initialization === + + olbInit( &argc, &argv ); + singleton::directories().setOutputDir( "./tmp/" ); + OstreamManager clout( std::cout,"main" ); + + UnitConverterFromResolutionAndRelaxationTime<T,DESCRIPTOR> converter( + (T) N, // resolution + (T) 1., // lattice relaxation time (tau) + (T) nx, // charPhysLength: reference length of simulation geometry + (T) 1.e-6, // charPhysVelocity: maximal/highest expected velocity during simulation in __m / s__ + (T) 0.1, // physViscosity: physical kinematic viscosity in __m^2 / s__ + (T) 1. // physDensity: physical density in __kg / m^3__ + ); + + // Prints the converter log as console output + converter.print(); + + // === 2nd Step: Prepare Geometry === + std::vector<T> extend = { nx, nx, nx }; + std::vector<T> origin = { 0, 0, 0 }; + IndicatorCuboid2D<T> cuboid(extend,origin); +#ifdef PARALLEL_MODE_MPI + CuboidGeometry2D<T> cGeometry( cuboid, converter.getPhysDeltaX(), singleton::mpi().getSize() ); +#else + CuboidGeometry2D<T> cGeometry( cuboid, converter.getPhysDeltaX() ); +#endif + + // set periodic boundaries to the domain + cGeometry.setPeriodicity( true, true ); + + // Instantiation of loadbalancer + HeuristicLoadBalancer<T> loadBalancer( cGeometry ); + loadBalancer.print(); + + // Instantiation of superGeometry + SuperGeometry2D<T> superGeometry( cGeometry,loadBalancer ); + + prepareGeometry( superGeometry ); + + // === 3rd Step: Prepare Lattice === + SuperLattice2D<T, DESCRIPTOR> sLattice1( superGeometry ); + SuperLattice2D<T, DESCRIPTOR> sLattice2( superGeometry ); + + ForcedBGKdynamics<T, DESCRIPTOR> bulkDynamics1 ( + converter.getLatticeRelaxationFrequency(), + instances::getBulkMomenta<T,DESCRIPTOR>() ); + + FreeEnergyBGKdynamics<T, DESCRIPTOR> bulkDynamics2 ( + converter.getLatticeRelaxationFrequency(), gama, + instances::getBulkMomenta<T,DESCRIPTOR>() ); + + prepareLattice( sLattice1, sLattice2, bulkDynamics1, bulkDynamics2, + converter, superGeometry ); + + prepareCoupling( sLattice1, sLattice2); + + SuperExternal2D<T,DESCRIPTOR,CHEM_POTENTIAL> sExternal1 (superGeometry, sLattice1, sLattice1.getOverlap() ); + SuperExternal2D<T,DESCRIPTOR,CHEM_POTENTIAL> sExternal2 (superGeometry, sLattice2, sLattice2.getOverlap() ); + + // === 4th Step: Main Loop with Timer === + int iT = 0; + clout << "starting simulation..." << endl; + Timer<T> timer( maxIter, superGeometry.getStatistics().getNvoxel() ); + timer.start(); + + for ( iT=0; iT<=maxIter; ++iT ) { + // Computation and output of the results + getResults( sLattice2, sLattice1, iT, superGeometry, timer, converter ); + + // Collide and stream execution + sLattice1.collideAndStream(); + sLattice2.collideAndStream(); + + // MPI communication for lattice data + sLattice1.communicate(); + sLattice2.communicate(); + + // Execute coupling between the two lattices + sLattice1.executeCoupling(); + sExternal1.communicate(); + sExternal2.communicate(); + sLattice2.executeCoupling(); + } + + timer.stop(); + timer.printSummary(); + +} |