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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
* which a Cell object can be instantiated -- generic implementation.
*/
#ifndef LB_GUOZHAO_DYNAMICS_HH
#define LB_GUOZHAO_DYNAMICS_HH
#include <algorithm>
#include <limits>
#include "dynamics/dynamics.h"
#include "core/cell.h"
#include "dynamics/guoZhaoLbHelpers.h"
#include "dynamics/firstOrderLbHelpers.h"
#include "dynamics/guoZhaoDynamics.h"
namespace olb {
////////////////////// Class GuoZhaoBGKdynamics /////////////////////////
/** \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>
GuoZhaoBGKdynamics<T,DESCRIPTOR>::GuoZhaoBGKdynamics (
T omega, Momenta<T,DESCRIPTOR>& momenta )
: BasicDynamics<T,DESCRIPTOR>(momenta),
_omega(omega)
{
OLB_PRECONDITION( DESCRIPTOR::template provides<descriptors::FORCE>() );
_epsilon = (T)1.0; // This to avoid a NaN error at the first timestep.
}
template<typename T, typename DESCRIPTOR>
T GuoZhaoBGKdynamics<T,DESCRIPTOR>::computeEquilibrium(int iPop, T rho, const T u[DESCRIPTOR::d], T uSqr) const
{
return GuoZhaoLbHelpers<T,DESCRIPTOR>::equilibrium(iPop, _epsilon, rho, u, uSqr);
}
template<typename T, typename DESCRIPTOR>
void GuoZhaoBGKdynamics<T,DESCRIPTOR>::computeU (Cell<T,DESCRIPTOR> const& cell, T u[DESCRIPTOR::d] ) const
{
T rho;
this->_momenta.computeRhoU(cell, rho, u);
for (int iVel=0; iVel<DESCRIPTOR::d; ++iVel) {
u[iVel] += cell.template getFieldPointer<descriptors::FORCE>()[iVel] / (T)2.;
}
}
template<typename T, typename DESCRIPTOR>
void GuoZhaoBGKdynamics<T,DESCRIPTOR>::computeRhoU (Cell<T,DESCRIPTOR> const& cell, T& rho, T u[DESCRIPTOR::d] ) const
{
this->_momenta.computeRhoU(cell, rho, u);
T epsilon = cell.template getFieldPointer<descriptors::EPSILON>()[0];
T nu = cell.template getFieldPointer<descriptors::NU>()[0];
T k = cell.template getFieldPointer<descriptors::K>()[0];
T Fe = 0.; //1.75/sqrt(150.*pow(epsilon,3));
T c_0 = 0.5*(1 + 0.5*epsilon*nu/k);
T c_1 = 0.5*epsilon*Fe/sqrt(k);
T uMag = 0.;
for (int iDim=0; iDim<DESCRIPTOR::d; ++iDim) {
uMag += u[iDim]*u[iDim];
}
uMag = sqrt(uMag);
for (int iDim=0; iDim<DESCRIPTOR::d; ++iDim) {
u[iDim] /= (c_0 + sqrt(c_0*c_0 + c_1*uMag));
u[iDim] += 0.5*epsilon*cell.template getFieldPointer<descriptors::BODY_FORCE>()[iDim];
}
}
template<typename T, typename DESCRIPTOR>
void GuoZhaoBGKdynamics<T,DESCRIPTOR>::updateEpsilon (Cell<T,DESCRIPTOR>& cell)
{
_epsilon = *cell.template getFieldPointer<descriptors::EPSILON>(); //Copying epsilon from
// external to member variable to provide access for computeEquilibrium.
}
template<typename T, typename DESCRIPTOR>
void GuoZhaoBGKdynamics<T,DESCRIPTOR>::collide (
Cell<T,DESCRIPTOR>& cell,
LatticeStatistics<T>& statistics )
{
// Copying epsilon from
// external to member variable to provide access for computeEquilibrium.
updateEpsilon(cell);
T rho, u[DESCRIPTOR::d];
this->_momenta.computeRhoU(cell, rho, u);
GuoZhaoLbHelpers<T,DESCRIPTOR>::updateGuoZhaoForce(cell, u);
T uSqr = GuoZhaoLbHelpers<T,DESCRIPTOR>::bgkCollision(cell, _epsilon, rho, u, _omega);
GuoZhaoLbHelpers<T,DESCRIPTOR>::addExternalForce(cell, u, _omega, rho, _epsilon);
statistics.incrementStats(rho, uSqr);
}
template<typename T, typename DESCRIPTOR>
T GuoZhaoBGKdynamics<T,DESCRIPTOR>::getOmega() const
{
return _omega;
}
template<typename T, typename DESCRIPTOR>
T GuoZhaoBGKdynamics<T,DESCRIPTOR>::getEpsilon()
{
return _epsilon;
}
template<typename T, typename DESCRIPTOR>
void GuoZhaoBGKdynamics<T,DESCRIPTOR>::setOmega(T omega)
{
_omega = omega;
}
}
#endif
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