Multicomponent flow

[Gloriousface]

Hello,

I want to use rayleighTaylor2d in the multicomponent model to simulate the flow of droplets in water. What kind of velocity boundary condition should I use?

Thanks,
Gloriousface

[mathias]

Dear Gloriousface,

look at the OpenLB examples. There is Rayleigh Taylor benchmark already available.

Best
Mathias

[Gloriousface]

Dear mathias，

Thank you for your reply.I tried to set the velocity of component 1 (water) at the entrance with setlocalVelocityboundary, but no flow occurred. Do I need to set a velocity boundary for component 2 (oil), such as setbouzidiVelocityboundary.

Best
Gloriousface

[mathias]

Yes, you need to set them for both components.

[Gloriousface]

Dear mathias，

Thank you for your reply.

Best
Gloriousface

[Gloriousface]

Hello mathias，

I’m trying to speed the oil drop. The code is as follows:

sLatticeOne.defineUbouzidi（superGeometry，5，poiseuilleU ）;
sLatticeTwo.defineUbouzidi（superGeometry，5，poiseuilleU ）;

Program output error reported as
class old::SuperLattice2D<double,old::descriptors::D2Q9<old::descriptors::VELOCITY,olb::descriptors::FORCE,olb::descriptors::EXTERNAL_FORCE,olb::descriptor::OMEGA> > has no member named “defineUBouzidi”

Could you tell me if defineubouzidi cannot be used in this model?

Best
Gloriousface

[Adrian]

defineUBouzidi is not a method of the super lattice but a free function that accepts the super lattice (sLatticeOne resp. sLatticeTwo in your case) as its first argument.

So this should look something like (I can not ensure that this works in this way exactly as I do not know your whole code):

defineUBouzidi(sLatticeOne, superGeometry, 5, poiseuilleU);
defineUBouzidi(sLatticeTwo, superGeometry, 5, poiseuilleU);

[Gloriousface]

There is a problem with the operation,Here is my complete code.

#include “olb2D.h”
#include “olb2D.hh” // use only generic version!
#include <cstdlib>
#include <iostream>

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

typedef double T;
typedef D2Q9<VELOCITY,FORCE,EXTERNAL_FORCE,OMEGA> DESCRIPTOR;

// Parameters for the simulation setup
const int nx = 300;
const int ny = 200;
const int maxIter = 20000;

// Stores geometry information in form of material numbers
void prepareGeometry( SuperGeometry2D<T>& superGeometry )
{

OstreamManager clout( std::cout,”prepareGeometry” );
clout << “Prepare Geometry …” << std::endl;

// Sets material number for fluid and boundary
//superGeometry.rename( 0,1 );

Vector<T,2> origin1( 0, 0 );
Vector<T,2> extend1( nx, ny );
IndicatorCuboid2D<T> inner( extend1, origin1 );

superGeometry.rename( 0,2 );
superGeometry.rename( 2,1,1,1 );

Vector<T,2> origin2( 0,0 );
Vector<T,2> extend2( 0, ny );
IndicatorCuboid2D<T> left( extend2, origin2 );
superGeometry.rename( 2,3,1,left );

Vector<T,2> origin3( nx, 0 );
Vector<T,2> extend3( 0, ny );
IndicatorCuboid2D<T> right( extend3, origin3 );
superGeometry.rename( 2,4,1,right );

Vector<T,2> center( nx/2, 30 );
IndicatorCircle2D<T> circle( center, 25 );
superGeometry.rename( 1,5,circle );

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

superGeometry.print();

clout << “Prepare Geometry … OK” << std::endl;
}

void prepareLattice( SuperLattice2D<T, DESCRIPTOR>& sLatticeOne,
SuperLattice2D<T, DESCRIPTOR>& sLatticeTwo,
Dynamics<T, DESCRIPTOR>& bulkDynamics1,
Dynamics<T, DESCRIPTOR>& bulkDynamics2,
Dynamics<T, DESCRIPTOR>& bounceBackRho0,
Dynamics<T, DESCRIPTOR>& bounceBackRho1,
SuperGeometry2D<T>& superGeometry )
{

OstreamManager clout( std::cout,”prepareLattice” );
clout << “Prepare Lattice …” << std::endl;

// The setup is: periodicity along horizontal direction, bounce-back on top
// and bottom. The upper half is initially filled with fluid 1 + random noise,
// and the lower half with fluid 2. Only fluid 1 experiences a forces,
// directed downwards.

const T omega = 1.0;

// define lattice Dynamics
sLatticeOne.defineDynamics( superGeometry, 0, &instances::getNoDynamics<T, DESCRIPTOR>() );
sLatticeTwo.defineDynamics( superGeometry, 0, &instances::getNoDynamics<T, DESCRIPTOR>() );

sLatticeOne.defineDynamics( superGeometry, 1, &bulkDynamics1 );
sLatticeOne.defineDynamics( superGeometry, 2, &bulkDynamics1 );
sLatticeOne.defineDynamics( superGeometry, 3, &bulkDynamics1 );
sLatticeOne.defineDynamics( superGeometry, 4, &bulkDynamics1 );
sLatticeOne.defineDynamics( superGeometry, 5, &bulkDynamics1 );
sLatticeTwo.defineDynamics( superGeometry, 1, &bulkDynamics2 );
sLatticeTwo.defineDynamics( superGeometry, 2, &bulkDynamics2 );
sLatticeTwo.defineDynamics( superGeometry, 3, &bulkDynamics2 );
sLatticeTwo.defineDynamics( superGeometry, 4, &bulkDynamics2 );
sLatticeTwo.defineDynamics( superGeometry, 5, &bulkDynamics2 );

sLatticeOne.defineDynamics( superGeometry, 2, &bounceBackRho0 );
sLatticeTwo.defineDynamics( superGeometry, 2, &bounceBackRho1 );
//sLatticeOne.defineDynamics( superGeometry, 4, &bounceBackRho1 );
//sLatticeTwo.defineDynamics( superGeometry, 4, &bounceBackRho0 );

setLocalVelocityBoundary<T,DESCRIPTOR>(sLatticeOne, omega, superGeometry, 3);
setLocalPressureBoundary<T,DESCRIPTOR>(sLatticeOne, omega, superGeometry, 4);
setLocalVelocityBoundary<T,DESCRIPTOR>(sLatticeTwo, omega, superGeometry, 3);
setLocalPressureBoundary<T,DESCRIPTOR>(sLatticeTwo, omega, superGeometry, 4);

Vector<T,2> center( nx/2,30 );
IndicatorCircle2D<T> circle ( center, 25 );
setBouzidiVelocityBoundary<T,DESCRIPTOR>(sLatticeOne, superGeometry, 5, circle);
setBouzidiVelocityBoundary<T,DESCRIPTOR>(sLatticeTwo, superGeometry, 5, circle);

clout << “Prepare Lattice … OK” << std::endl;
}

void setBoundaryValues( SuperLattice2D<T, DESCRIPTOR>& sLatticeOne,
SuperLattice2D<T, DESCRIPTOR>& sLatticeTwo,
T force, int iT, SuperGeometry2D<T>& superGeometry )
{
if ( iT==0 ) {

AnalyticalConst2D<T,T> noise( 4.e-2 );
std::vector<T> v( 2,T() );
AnalyticalConst2D<T,T> zeroV( v );
AnalyticalConst2D<T,T> zero( 1.e-6 );
AnalyticalLinear2D<T,T> one( 0.,-force*invCs2<T,DESCRIPTOR>(),0.98+force*ny*invCs2<T,DESCRIPTOR>() );
AnalyticalConst2D<T,T> onePlus( 0.98+force*ny/2.*invCs2<T,DESCRIPTOR>() );
AnalyticalRandom2D<T,T> random;
AnalyticalIdentity2D<T,T> randomOne( random*noise+one );
AnalyticalIdentity2D<T,T> randomPlus( random*noise+onePlus );
std::vector<T> F( 2,T() );
F[1] = -force;
AnalyticalConst2D<T,T> f( F );

// for each material set the defineRhou and the Equilibrium

sLatticeOne.defineRhoU( superGeometry, 5, zero, zeroV );
sLatticeOne.iniEquilibrium( superGeometry, 5, zero, zeroV );
sLatticeOne.defineField<descriptors::EXTERNAL_FORCE>( superGeometry, 5, f );
sLatticeTwo.defineRhoU( superGeometry, 5, randomPlus, zeroV );
sLatticeTwo.iniEquilibrium( superGeometry, 5, randomPlus, zeroV );

sLatticeOne.defineRhoU( superGeometry, 1, randomOne, zeroV );
sLatticeOne.iniEquilibrium( superGeometry, 1, randomOne, zeroV );
sLatticeOne.defineField<descriptors::EXTERNAL_FORCE>( superGeometry, 1, f );
sLatticeTwo.defineRhoU( superGeometry, 1, zero, zeroV );
sLatticeTwo.iniEquilibrium( superGeometry, 1, zero, zeroV );

sLatticeOne.defineRhoU(superGeometry, 2, zero, zeroV);
sLatticeOne.iniEquilibrium(superGeometry, 2, zero, zeroV);
sLatticeOne.defineField<descriptors::EXTERNAL_FORCE>(superGeometry, 2, f);
sLatticeTwo.defineRhoU(superGeometry, 2, one, zeroV);
sLatticeTwo.iniEquilibrium(superGeometry, 2, one, zeroV);

sLatticeOne.defineRhoU(superGeometry, 3, one, zeroV);
sLatticeOne.iniEquilibrium(superGeometry, 3, one, zeroV);
sLatticeOne.defineField<descriptors::EXTERNAL_FORCE>(superGeometry, 3, f);
sLatticeTwo.defineRhoU(superGeometry, 3, zero, zeroV);
sLatticeTwo.iniEquilibrium(superGeometry, 3, zero, zeroV);

sLatticeOne.defineRhoU(superGeometry, 4, one, zeroV);
sLatticeOne.iniEquilibrium(superGeometry, 4, one, zeroV);
sLatticeOne.defineField<descriptors::EXTERNAL_FORCE>(superGeometry, 4, f);
sLatticeTwo.defineRhoU(superGeometry, 4, zero, zeroV);
sLatticeTwo.iniEquilibrium(superGeometry, 4, zero, zeroV);

PolynomialStartScale<T,T> StartScale( 20000, T( 1 ) );

// Creates and sets the Poiseuille inflow profile using functors
T iTvec[1] = {T( iT )};
T frac[1] = {};
StartScale( frac,iTvec );
T maxVelocity = 0.1*3./2.*frac[0];
T distance2Wall = 0.01/2.;
Poiseuille2D<T> poiseuilleU( superGeometry, 3, maxVelocity, distance2Wall );

sLatticeOne.defineU( superGeometry, 3, poiseuilleU );
sLatticeTwo.defineU( superGeometry, 3, poiseuilleU );
//sLatticeOne.defineUBouzidi( superGeometry, 5, poiseuilleU );
//sLatticeTwo.defineUBouzidi( superGeometry, 5, poiseuilleU );
defineUBouzidi<T,DESCRIPTOR>(sLatticeOne, superGeometry,5,poiseuilleU );
defineUBouzidi<T,DESCRIPTOR>(sLatticeTwo, superGeometry,5,poiseuilleU );
// Make the lattice ready for simulation
sLatticeOne.initialize();
sLatticeTwo.initialize();
}
}

void getResults( SuperLattice2D<T, DESCRIPTOR>& sLatticeTwo,
SuperLattice2D<T, DESCRIPTOR>& sLatticeOne, int iT,
SuperGeometry2D<T>& superGeometry, Timer<T>& timer )
{

OstreamManager clout( std::cout,”getResults” );
SuperVTMwriter2D<T> vtmWriter( “rayleighTaylor2dsLatticeOne” );

const int vtkIter = 100;
const int statIter = 10;

if ( iT==0 ) {
// Writes the geometry, cuboid no. and rank no. as vti file for visualization
SuperLatticeGeometry2D<T, DESCRIPTOR> geometry( sLatticeOne, superGeometry );
SuperLatticeCuboid2D<T, DESCRIPTOR> cuboid( sLatticeOne );
SuperLatticeRank2D<T, DESCRIPTOR> rank( sLatticeOne );
vtmWriter.write( geometry );
vtmWriter.write( cuboid );
vtmWriter.write( rank );
vtmWriter.createMasterFile();
}

// Get statistics
if ( iT%statIter==0 && iT > 0 ) {
// Timer console output
timer.update( iT );
timer.printStep();

clout << “averageRhoFluidOne=” << sLatticeOne.getStatistics().getAverageRho();
clout << “; averageRhoFluidTwo=” << sLatticeTwo.getStatistics().getAverageRho() << std::endl;
}

// Writes the VTK files
if ( iT%vtkIter==0 ) {
clout << “Writing VTK …” << std::endl;
SuperLatticeVelocity2D<T, DESCRIPTOR> velocity( sLatticeOne );
SuperLatticeDensity2D<T, DESCRIPTOR> density( sLatticeOne );
vtmWriter.addFunctor( velocity );
vtmWriter.addFunctor( density );
vtmWriter.write( iT );

BlockReduction2D2D<T> planeReduction( density, 600, BlockDataSyncMode::ReduceOnly );
// write output as JPEG
heatmap::write(planeReduction, iT);

clout << “Writing VTK … OK” << std::endl;
}
}

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

// === 1st Step: Initialization ===

olbInit( &argc, &argv );
singleton::directories().setOutputDir( “./tmp/” );
OstreamManager clout( std::cout,”main” );

const T omega1 = 1.0;
const T omega2 = 1.0;
const T G = 3.;
T force = 30./( T )ny/( T )ny;

// === 2nd Step: Prepare Geometry ===
// Instantiation of a cuboidGeometry with weights

#ifdef PARALLEL_MODE_MPI
CuboidGeometry2D<T> cGeometry( 0, 0, 1, nx, ny, singleton::mpi().getSize() );
#else
CuboidGeometry2D<T> cGeometry( 0, 0, 1, nx, ny, 1 );
#endif

cGeometry.setPeriodicity( true, false );

HeuristicLoadBalancer<T> loadBalancer( cGeometry );

SuperGeometry2D<T> superGeometry( cGeometry, loadBalancer, 2 );

prepareGeometry( superGeometry );

// === 3rd Step: Prepare Lattice ===

SuperLattice2D<T, DESCRIPTOR> sLatticeOne( superGeometry );
SuperLattice2D<T, DESCRIPTOR> sLatticeTwo( superGeometry );

ForcedBGKdynamics<T, DESCRIPTOR> bulkDynamics1 (
omega1, instances::getExternalVelocityMomenta<T,DESCRIPTOR>() );
ForcedBGKdynamics<T, DESCRIPTOR> bulkDynamics2 (
omega2, instances::getExternalVelocityMomenta<T,DESCRIPTOR>() );

// A bounce-back node with fictitious density 1,
// which is experienced by the partner fluid
BounceBack<T, DESCRIPTOR> bounceBackRho1( 1. );
// A bounce-back node with fictitious density 0,
// which is experienced by the partner fluid
BounceBack<T, DESCRIPTOR> bounceBackRho0( 0. );

std::vector<T> rho0;
rho0.push_back( 1 );
rho0.push_back( 1 );
PsiEqualsRho<T,T> interactionPotential;
ShanChenForcedGenerator2D<T,DESCRIPTOR> coupling( G,rho0,interactionPotential );

sLatticeOne.addLatticeCoupling( coupling, sLatticeTwo );

prepareLattice( sLatticeOne, sLatticeTwo, bulkDynamics1, bulkDynamics2,
bounceBackRho0, bounceBackRho1, superGeometry );

// === 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 ) {

// === 5th Step: Definition of Initial and Boundary Conditions ===
setBoundaryValues( sLatticeOne, sLatticeTwo, force, iT, superGeometry );

// === 6th Step: Collide and Stream Execution ===
sLatticeOne.collideAndStream();
sLatticeTwo.collideAndStream();

sLatticeOne.communicate();
sLatticeTwo.communicate();

sLatticeOne.executeCoupling();
//sLatticeTwo.executeCoupling();

// === 7th Step: Computation and Output of the Results ===
getResults( sLatticeTwo, sLatticeOne, iT, superGeometry, timer );
}

timer.stop();
timer.printSummary();
}

Thanks

[Author]

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