path: root/examples/laminar/cylinder3d/cylinder3d.cpp

/*  Lattice Boltzmann sample, written in C++, using the OpenLB
 *  library
 *
 *  Copyright (C) 2011-2013 Mathias J. Krause, Thomas Henn, Tim Dornieden
 *  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.
 */

/* cylinder3d.cpp:
 * This example examines a steady flow past a cylinder placed in a channel.
 * The cylinder is offset somewhat from the center of the flow to make the
 * steady-state symmetrical flow unstable. At the inlet, a Poiseuille profile is
 * imposed on the velocity, whereas the outlet implements a Dirichlet pressure
 * condition set by p = 0.
 * Inspired by "Benchmark Computations of Laminar Flow Around
 * a Cylinder" by M.Schäfer and S.Turek. For high resolution, low
 * latticeU, and enough time to converge, the results for pressure drop, drag
 * and lift lie within the estimated intervals for the exact results.
 * An unsteady flow with Karman vortex street can be created by changing the
 * Reynolds number to Re=100.
 * It also shows the usage of the STL-reader and explains how
 * to set boundary conditions automatically.
 */


#include "olb3D.h"
#ifndef OLB_PRECOMPILED // Unless precompiled version is used,
#include "olb3D.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 olb::util;
using namespace std;

typedef double T;
#define DESCRIPTOR D3Q19<>


// Parameters for the simulation setup
const int N = 10;        // resolution of the model
const T Re = 20.;       // Reynolds number
const T maxPhysT = 16.; // max. simulation time in s, SI unit


// Stores data from stl file in geometry in form of material numbers
void prepareGeometry( UnitConverter<T,DESCRIPTOR> const& converter, IndicatorF3D<T>& indicator,
                      STLreader<T>& stlReader, SuperGeometry3D<T>& superGeometry ) {

  OstreamManager clout( std::cout,"prepareGeometry" );
  clout << "Prepare Geometry ..." << std::endl;

  superGeometry.rename( 0,2,indicator );
  superGeometry.rename( 2,1,stlReader );
  superGeometry.clean();

  Vector<T,3> origin = superGeometry.getStatistics().getMinPhysR( 2 );
  origin[1] += converter.getConversionFactorLength()/2.;
  origin[2] += converter.getConversionFactorLength()/2.;

  Vector<T,3> extend = superGeometry.getStatistics().getMaxPhysR( 2 );
  extend[1] = extend[1]-origin[1]-converter.getConversionFactorLength()/2.;
  extend[2] = extend[2]-origin[2]-converter.getConversionFactorLength()/2.;

  // Set material number for inflow
  origin[0] = superGeometry.getStatistics().getMinPhysR( 2 )[0]-converter.getConversionFactorLength();
  extend[0] = 2*converter.getConversionFactorLength();
  IndicatorCuboid3D<T> inflow( extend,origin );
  superGeometry.rename( 2,3,inflow );

  // Set material number for outflow
  origin[0] = superGeometry.getStatistics().getMaxPhysR( 2 )[0]-converter.getConversionFactorLength();
  extend[0] = 2*converter.getConversionFactorLength();
  IndicatorCuboid3D<T> outflow( extend,origin );
  superGeometry.rename( 2,4,outflow );

  // Set material number for cylinder
  origin[0] = superGeometry.getStatistics().getMinPhysR( 2 )[0]+converter.getConversionFactorLength();
  extend[0] = ( superGeometry.getStatistics().getMaxPhysR( 2 )[0]-superGeometry.getStatistics().getMinPhysR( 2 )[0] )/2.;
  IndicatorCuboid3D<T> cylinder( extend,origin );
  superGeometry.rename( 2,5,cylinder );

  // Removes all not needed boundary voxels outside the surface
  superGeometry.clean();
  superGeometry.checkForErrors();

  superGeometry.print();

  clout << "Prepare Geometry ... OK" << std::endl;
}

// Set up the geometry of the simulation
void prepareLattice( SuperLattice3D<T,DESCRIPTOR>& sLattice,
                     UnitConverter<T,DESCRIPTOR> const& converter,
                     Dynamics<T, DESCRIPTOR>& bulkDynamics,
                     sOnLatticeBoundaryCondition3D<T,DESCRIPTOR>& bc,
                     sOffLatticeBoundaryCondition3D<T,DESCRIPTOR>& offBc,
                     STLreader<T>& stlReader,
                     SuperGeometry3D<T>& superGeometry ) {

  OstreamManager clout( std::cout,"prepareLattice" );
  clout << "Prepare Lattice ..." << std::endl;

  const T omega = converter.getLatticeRelaxationFrequency();

  // Material=0 -->do nothing
  sLattice.defineDynamics( superGeometry, 0, &instances::getNoDynamics<T, DESCRIPTOR>() );

  // Material=1 -->bulk dynamics
  // Material=3 -->bulk dynamics (inflow)
  // Material=4 -->bulk dynamics (outflow)
  auto bulkIndicator = superGeometry.getMaterialIndicator({1, 3, 4});
  sLattice.defineDynamics( bulkIndicator, &bulkDynamics );

  // Material=2 -->bounce back
  sLattice.defineDynamics( superGeometry, 2, &instances::getBounceBack<T, DESCRIPTOR>() );

  // Setting of the boundary conditions
  bc.addVelocityBoundary( superGeometry, 3, omega );
  bc.addPressureBoundary( superGeometry, 4, omega );

  // Material=5 -->bouzidi
  sLattice.defineDynamics( superGeometry, 5, &instances::getNoDynamics<T,DESCRIPTOR>() );
  offBc.addZeroVelocityBoundary( superGeometry, 5, stlReader );

  // Initial conditions
  AnalyticalConst3D<T,T> rhoF( 1 );
  Vector<T,3> velocityV;
  AnalyticalConst3D<T,T> uF(velocityV);

  // Initialize all values of distribution functions to their local equilibrium
  sLattice.defineRhoU( bulkIndicator, rhoF, uF );
  sLattice.iniEquilibrium( bulkIndicator, rhoF, uF );

  // Make the lattice ready for simulation
  sLattice.initialize();

  clout << "Prepare Lattice ... OK" << std::endl;
}

// Generates a slowly increasing inflow for the first iTMaxStart timesteps
void setBoundaryValues( SuperLattice3D<T, DESCRIPTOR>& sLattice,
                        UnitConverter<T,DESCRIPTOR> const& converter, int iT,
                        SuperGeometry3D<T>& superGeometry ) {

  OstreamManager clout( std::cout,"setBoundaryValues" );

  // No of time steps for smooth start-up
  int iTmaxStart = converter.getLatticeTime( maxPhysT*0.4 );
  int iTupdate = 30;

  if ( iT%iTupdate == 0 && iT <= iTmaxStart ) {
    // Smooth start curve, sinus
    // SinusStartScale<T,int> StartScale(iTmaxStart, T(1));

    // Smooth start curve, polynomial
    PolynomialStartScale<T,int> StartScale( iTmaxStart, T( 1 ) );

    // Creates and sets the Poiseuille inflow profile using functors
    int iTvec[1] = {iT};
    T frac[1] = {};
    StartScale( frac,iTvec );
    std::vector<T> maxVelocity( 3,0 );
    maxVelocity[0] = 2.25*frac[0]*converter.getCharLatticeVelocity();

    T distance2Wall = converter.getConversionFactorLength()/2.;
    RectanglePoiseuille3D<T> poiseuilleU( superGeometry, 3, maxVelocity, distance2Wall, distance2Wall, distance2Wall );
    sLattice.defineU( superGeometry, 3, poiseuilleU );

    clout << "step=" << iT << "; maxVel=" << maxVelocity[0] << std::endl;
  }
}

// Computes the pressure drop between the voxels before and after the cylinder
void getResults( SuperLattice3D<T, DESCRIPTOR>& sLattice,
                 UnitConverter<T,DESCRIPTOR> const& converter, int iT,
                 SuperGeometry3D<T>& superGeometry, Timer<T>& timer,
                 STLreader<T>& stlReader ) {

  OstreamManager clout( std::cout,"getResults" );

  SuperVTMwriter3D<T> vtmWriter( "cylinder3d" );
  SuperLatticePhysVelocity3D<T, DESCRIPTOR> velocity( sLattice, converter );
  SuperLatticePhysPressure3D<T, DESCRIPTOR> pressure( sLattice, converter );
  SuperLatticeYplus3D<T, DESCRIPTOR> yPlus( sLattice, converter, superGeometry, stlReader, 5 );
  vtmWriter.addFunctor( velocity );
  vtmWriter.addFunctor( pressure );
  vtmWriter.addFunctor( yPlus );

  const int vtkIter  = converter.getLatticeTime( .3 );
  const int statIter = converter.getLatticeTime( .1 );

  if ( iT==0 ) {
    // Writes the geometry, cuboid no. and rank no. as vti file for visualization
    SuperLatticeGeometry3D<T, DESCRIPTOR> geometry( sLattice, superGeometry );
    SuperLatticeCuboid3D<T, DESCRIPTOR> cuboid(