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/* This file is part of the OpenLB library
*
* Copyright (C) 2006, 2007 Jonas Latt
* 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.
*/
/** \file
* A collection of dynamics classes (e.g. BGK) with which a Cell object
* can be instantiated -- generic implementation.
*/
#ifndef MRT_DYNAMICS_HH
#define MRT_DYNAMICS_HH
#include <algorithm>
#include <limits>
#include "mrtHelpers.h"
namespace olb {
//==============================================================================//
/////////////////////////// Class MRTdynamics ///////////////////////////////
//==============================================================================//
/** \param omega_ relaxation parameter, related to the dynamic viscosity
* \param momenta_ a Momenta object to know how to compute velocity momenta
* \param lambda_ will be used as an
*/
// Original implementation based on:
// D'Humieres et al., "Multiple-relaxation-time lattice Boltzmann models in three dimensions",
// Phil: Trans. R. soc. Lond. A (2002) 360, 437-451
// and
// Yu et al,, "LES of turbulent square jet flow using an MRT lattice Boltzmann model",
// Computers & Fluids 35 (2006), 957-965
template<typename T, typename DESCRIPTOR>
MRTdynamics<T,DESCRIPTOR>::MRTdynamics (
T omega_, Momenta<T,DESCRIPTOR>& momenta_ )
: BasicDynamics<T,DESCRIPTOR>(momenta_), omega(omega_), lambda(omega_)
{
T rt[DESCRIPTOR::q]; // relaxation times vector.
for (int iPop = 0; iPop < DESCRIPTOR::q; ++iPop) {
rt[iPop] = descriptors::s<T,DESCRIPTOR>(iPop);
}
for (int iPop = 0; iPop < descriptors::shearIndexes<DESCRIPTOR>(); ++iPop) {
rt[descriptors::shearViscIndexes<DESCRIPTOR>(iPop)] = omega;
}
for (int iPop = 0; iPop < DESCRIPTOR::q; ++iPop) {
for (int jPop = 0; jPop < DESCRIPTOR::q; ++jPop) {
invM_S[iPop][jPop] = T();
for (int kPop = 0; kPop < DESCRIPTOR::q; ++kPop) {
if (kPop == jPop) {
invM_S[iPop][jPop] += descriptors::invM<T,DESCRIPTOR>(iPop,kPop) *
rt[kPop];
}
}
}
}
}
template<typename T, typename DESCRIPTOR>
T MRTdynamics<T,DESCRIPTOR>::computeEquilibrium(int iPop, T rho, const T u[DESCRIPTOR::d], T uSqr) const
{
return lbHelpers<T,DESCRIPTOR>::equilibrium(iPop, rho, u, uSqr);
}
template<typename T, typename DESCRIPTOR>
void MRTdynamics<T,DESCRIPTOR>::computeAllEquilibrium(T momentaEq[DESCRIPTOR::q],
T rho, const T u[DESCRIPTOR::d],
const T uSqr)
{
mrtHelpers<T,DESCRIPTOR>::computeEquilibrium(momentaEq, rho, u, uSqr);
}
template<typename T, typename DESCRIPTOR>
void MRTdynamics<T,DESCRIPTOR>::collide (
Cell<T,DESCRIPTOR>& cell,
LatticeStatistics<T>& statistics )
{
typedef DESCRIPTOR L;
typedef mrtHelpers<T,DESCRIPTOR> mrtH;
T rho, u[L::d];
this->_momenta.computeRhoU(cell, rho, u);
T uSqr = mrtH::mrtCollision(cell,rho,u,invM_S);
statistics.incrementStats(rho, uSqr);
}
template<typename T, typename DESCRIPTOR>
T MRTdynamics<T,DESCRIPTOR>::getOmega() const
{
return omega;
}
template<typename T, typename DESCRIPTOR>
void MRTdynamics<T,DESCRIPTOR>::setOmega(T omega_)
{
omega = omega_;
}
template<typename T, typename DESCRIPTOR>
T MRTdynamics<T,DESCRIPTOR>::getLambda() const
{
return lambda;
}
template<typename T, typename DESCRIPTOR>
void MRTdynamics<T,DESCRIPTOR>::setLambda(T lambda_)
{
lambda = lambda_;
}
template<typename T, typename DESCRIPTOR>
MRTdynamics2<T,DESCRIPTOR>::MRTdynamics2 (
T omega_, Momenta<T,DESCRIPTOR>& momenta_ )
: MRTdynamics<T,DESCRIPTOR>(omega_, momenta_)
{
T rt[DESCRIPTOR::q]; // relaxation times vector.
for (int iPop = 0; iPop < DESCRIPTOR::q; ++iPop) {
rt[iPop] = descriptors::s_2<T,DESCRIPTOR>(iPop);
}
for (int iPop = 0; iPop < descriptors::shearIndexes<DESCRIPTOR>(); ++iPop) {
rt[descriptors::shearViscIndexes<DESCRIPTOR>(iPop)] = omega;
}
for (int iPop = 0; iPop < DESCRIPTOR::q; ++iPop) {
for (int jPop = 0; jPop < DESCRIPTOR::q; ++jPop) {
invM_S_2[iPop][jPop] = T();
for (int kPop = 0; kPop < DESCRIPTOR::q; ++kPop) {
if (kPop == jPop) {
invM_S_2[iPop][jPop] += descriptors::invM<T,DESCRIPTOR>(iPop,kPop) *
rt[kPop];
}
}
}
}
}
// Stabalized MRT scheme with uniform relaxation times
template<typename T, typename DESCRIPTOR>
void MRTdynamics2<T,DESCRIPTOR>::collide (
Cell<T,DESCRIPTOR>& cell,
LatticeStatistics<T>& statistics )
{
typedef mrtHelpers<T,DESCRIPTOR> mrtH;
T rho, u[DESCRIPTOR::d];
this->_momenta.computeRhoU(cell, rho, u);
T uSqr = mrtH::mrtCollision(cell,rho,u,invM_S_2);
statistics.incrementStats(rho, uSqr);
}
template<typename T, typename DESCRIPTOR>
ForcedMRTdynamics<T,DESCRIPTOR>::ForcedMRTdynamics (
T omega_, Momenta<T,DESCRIPTOR>& momenta_ )
: MRTdynamics<T,DESCRIPTOR>(omega_, momenta_)
{
}
template<typename T, typename DESCRIPTOR>
void ForcedMRTdynamics<T,DESCRIPTOR>::collide (
Cell<T,DESCRIPTOR>& cell,
LatticeStatistics<T>& statistics )
{
T rho, u[DESCRIPTOR::d];
this->_momenta.computeRhoU(cell, rho, u);
T uSqr = mrtHelpers<T,DESCRIPTOR>::mrtCollision(cell, rho, u, this->invM_S);
mrtHelpers<T,DESCRIPTOR>::addExternalForce(cell, rho, u, this->invM_S);
statistics.incrementStats(rho, uSqr);
}
} // end namespace
#endif
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