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/* This file is part of the OpenLB library
*
* Copyright (C) 2012 Patrick Nathen, Mathias J. Krause
* 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
* MRT Dynamics with adjusted omega -- generic implementation.
*/
#ifndef SMAGORINSKY_MRT_DYNAMICS_HH
#define SMAGORINSKY_MRT_DYNAMICS_HH
#include <algorithm>
#include <limits>
#include "smagorinskyMRTdynamics.h"
#include "mrtDynamics.h"
#include "mrtHelpers.h"
#include "core/cell.h"
#include "core/util.h"
#include "math.h"
using namespace std;
namespace olb {
////////////////////// Class SmagorinskyMRTdynamics //////////////////////////
/** \param vs2_ speed of sound
* \param momenta_ a Momenta object to know how to compute velocity momenta
* \param momenta_ a Momenta object to know how to compute velocity momenta
*/
template<typename T, typename DESCRIPTOR>
SmagorinskyMRTdynamics<T,DESCRIPTOR>::SmagorinskyMRTdynamics (
T omega_, Momenta<T,DESCRIPTOR>& momenta_, T smagoConst_, T dx_, T dt_ )
: MRTdynamics<T,DESCRIPTOR>(omega_, momenta_/*, smagoConst_*/),
smagoConst(smagoConst_),
preFactor(computePreFactor(omega_,smagoConst_) )
{
T rtSGS[DESCRIPTOR::q]; // relaxation times vector for SGS approach.
for (int iPop = 0; iPop < DESCRIPTOR::q; ++iPop) {
rtSGS[iPop] = DESCRIPTOR::S[iPop];
}
for (int iPop = 0; iPop < DESCRIPTOR::shearIndexes; ++iPop) {
rtSGS[DESCRIPTOR::shearViscIndexes[iPop]] = omega;
}
for (int iPop = 0; iPop < DESCRIPTOR::q; ++iPop) {
for (int jPop = 0; jPop < DESCRIPTOR::q; ++jPop) {
invM_S_SGS[iPop][jPop] = T();
for (int kPop = 0; kPop < DESCRIPTOR::q; ++kPop) {
if (kPop == jPop) {
invM_S_SGS[iPop][jPop] += DESCRIPTOR::invM[iPop][kPop] * rtSGS[kPop];
}
}
}
}
}
template<typename T, typename DESCRIPTOR>
void SmagorinskyMRTdynamics<T,DESCRIPTOR>::collide(
Cell<T,DESCRIPTOR>& cell,
LatticeStatistics<T>& statistics )
{
T rho, u[DESCRIPTOR::d], pi[util::TensorVal<DESCRIPTOR >::n];
this->_momenta.computeAllMomenta(cell, rho, u, pi);
T newOmega = computeOmega(this->getOmega(), preFactor, rho, pi);
for (int iPop = 0; iPop < DESCRIPTOR::q; ++iPop) {
for (int jPop = 0; jPop < DESCRIPTOR::shearIndexes; ++jPop) {
invM_S_SGS[iPop][DESCRIPTOR::shearViscIndexes[jPop]] = DESCRIPTOR::invM[iPop][DESCRIPTOR::shearViscIndexes[jPop]] * newOmega;
}
}
T uSqr = mrtHelpers<T,DESCRIPTOR>::mrtSGSCollision(cell, rho, u, newOmega, invM_S_SGS);
statistics.incrementStats(rho, uSqr);
}
template<typename T, typename DESCRIPTOR>
void SmagorinskyMRTdynamics<T,DESCRIPTOR>::setOmega(T omega)
{
this->setOmega(omega);
preFactor = computePreFactor(omega, smagoConst);
}
template<typename T, typename DESCRIPTOR>
T SmagorinskyMRTdynamics<T,DESCRIPTOR>::getSmagorinskyOmega(Cell<T,DESCRIPTOR>& cell )
{
T rho, uTemp[DESCRIPTOR::d], pi[util::TensorVal<DESCRIPTOR >::n];
this->_momenta.computeAllMomenta(cell, rho, uTemp, pi);
T newOmega = computeOmega(this->getOmega(), preFactor, rho, pi);
return newOmega;
}
template<typename T, typename DESCRIPTOR>
T SmagorinskyMRTdynamics<T,DESCRIPTOR>::computePreFactor(T omega, T smagoConst)
{
return (T)smagoConst*smagoConst*descriptors::invCs2<T,DESCRIPTOR>()*descriptors::invCs2<T,DESCRIPTOR>()*2*sqrt(2);
}
template<typename T, typename DESCRIPTOR>
T SmagorinskyMRTdynamics<T,DESCRIPTOR>::computeOmega(T omega0, T preFactor, T rho, T pi[util::TensorVal<DESCRIPTOR >::n] )
{
T PiNeqNormSqr = pi[0]*pi[0] + 2.0*pi[1]*pi[1] + pi[2]*pi[2];
if (util::TensorVal<DESCRIPTOR >::n == 6) {
PiNeqNormSqr += pi[2]*pi[2] + pi[3]*pi[3] + 2*pi[4]*pi[4] +pi[5]*pi[5];
}
T PiNeqNorm = sqrt(PiNeqNormSqr);
/// Molecular realaxation time
T tau_mol = 1. /omega0;
/// Turbulent realaxation time
T tau_turb = 0.5*(sqrt(tau_mol*tau_mol + preFactor/rho*PiNeqNorm) - tau_mol);
/// Effective realaxation time
tau_eff = tau_mol+tau_turb;
T omega_new= 1./tau_eff;
return omega_new;
}
template<typename T, typename DESCRIPTOR>
void SmagorinskyForcedMRTdynamics<T,DESCRIPTOR>::collide(
Cell<T,DESCRIPTOR>& cell,
LatticeStatistics<T>& statistics )
{
T rho, u[DESCRIPTOR::d], pi[util::TensorVal<DESCRIPTOR >::n];
this->_momenta.computeAllMomenta(cell, rho, u, pi);
T newOmega = computeOmega(this->getOmega(), this->preFactor, rho, pi);
for (int iPop = 0; iPop < DESCRIPTOR::q; ++iPop) {
for (int jPop = 0; jPop < DESCRIPTOR::shearIndexes; ++jPop) {
this->invM_S_SGS[iPop][DESCRIPTOR::shearViscIndexes[jPop]] = DESCRIPTOR::invM[iPop][DESCRIPTOR::shearViscIndexes[jPop]] * newOmega;
}
}
T uSqr = mrtHelpers<T,DESCRIPTOR>::mrtSGSCollision(cell, rho, u, newOmega, this->invM_S_SGS);
mrtHelpers<T,DESCRIPTOR>::addExternalForce(cell, rho, u, this->invM_S_SGS);
statistics.incrementStats(rho, uSqr);
}
}
#endif
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