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/* This file is part of the OpenLB library
*
* Copyright (C) 2016-2017 Davide Dapelo, Mathias J. Krause
* OpenLB 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
* Specific dynamics classes for Guo and Zhao (2002) porous model
* with a Smagorinsky LES turbulence model, with
* which a Cell object can be instantiated -- generic implementation.
*/
#ifndef LB_SMAGO_GUOZHAO_DYNAMICS_HH
#define LB_SMAGO_GUOZHAO_DYNAMICS_HH
#include <algorithm>
#include <limits>
#include "dynamics/dynamics.h"
#include "core/cell.h"
#include "dynamics/guoZhaoLbHelpers.h"
#include "dynamics/firstOrderLbHelpers.h"
namespace olb {
////////////////////// Class SmagorinskyGuoZhaoBGKdynamics /////////////////////////
/** \param omega_ relaxation parameter, related to the dynamic viscosity
* \param momenta_ a Momenta object to know how to compute velocity momenta
*/
template<typename T, typename DESCRIPTOR>
SmagorinskyGuoZhaoBGKdynamics<T,DESCRIPTOR>::SmagorinskyGuoZhaoBGKdynamics (T omega_,
Momenta<T,DESCRIPTOR>& momenta_, T smagoConst_, T dx_, T dt_ )
: GuoZhaoBGKdynamics<T,DESCRIPTOR>(omega_,momenta_), smagoConst(smagoConst_),
preFactor(computePreFactor(omega_,smagoConst_) )
{ }
template<typename T, typename DESCRIPTOR>
void SmagorinskyGuoZhaoBGKdynamics<T,DESCRIPTOR>::collide (
Cell<T,DESCRIPTOR>& cell,
LatticeStatistics<T>& statistics )
{
// Copying epsilon from
// external to member variable to provide access for computeEquilibrium.
this->updateEpsilon(cell);
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);
T* force = cell.template getFieldPointer<descriptors::FORCE>();
for (int iVel=0; iVel<DESCRIPTOR::d; ++iVel) {
u[iVel] += force[iVel] / (T)2.;
}
T uSqr = GuoZhaoLbHelpers<T,DESCRIPTOR>::bgkCollision(cell, this->getEpsilon(), rho, u, newOmega);
GuoZhaoLbHelpers<T,DESCRIPTOR>::updateGuoZhaoForce(cell, u);
lbHelpers<T,DESCRIPTOR>::addExternalForce(cell, u, newOmega, rho);
statistics.incrementStats(rho, uSqr);
}
template<typename T, typename DESCRIPTOR>
T SmagorinskyGuoZhaoBGKdynamics<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 SmagorinskyGuoZhaoBGKdynamics<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>
void SmagorinskyGuoZhaoBGKdynamics<T,DESCRIPTOR>::setOmega(T omega)
{
// _omega = omega;
GuoZhaoBGKdynamics<T,DESCRIPTOR>::setOmega(omega);
preFactor = computePreFactor(omega, smagoConst);
}
template<typename T, typename DESCRIPTOR>
T SmagorinskyGuoZhaoBGKdynamics<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;
}
}
#endif
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