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/* This file is part of the OpenLB library
*
* Copyright (C) 2008 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
* BGK Dynamics with adjustable speed of sound -- generic implementation.
*/
#ifndef CHOPARD_DYNAMICS_HH
#define CHOPARD_DYNAMICS_HH
#include "chopardDynamics.h"
#include "core/util.h"
namespace olb {
////////////////////// Class ChopardDynamics //////////////////////////
/** \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>
ChopardDynamics<T,DESCRIPTOR>::ChopardDynamics (
T vs2_, T omega_, Momenta<T,DESCRIPTOR>& momenta_ )
: BasicDynamics<T,DESCRIPTOR>(momenta_),
vs2(vs2_),
omega(omega_)
{ }
/** With this constructor, the speed of sound is vs2 = cs2
* \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>
ChopardDynamics<T,DESCRIPTOR>::ChopardDynamics (
T omega_, Momenta<T,DESCRIPTOR>& momenta_ )
: BasicDynamics<T,DESCRIPTOR>(momenta_),
vs2((T)1/descriptors::invCs2<T,DESCRIPTOR>()),
omega(omega_)
{ }
template<typename T, typename DESCRIPTOR>
T ChopardDynamics<T,DESCRIPTOR>::computeEquilibrium
(int iPop, T rho, const T u[DESCRIPTOR::d], T uSqr) const
{
return chopardEquilibrium(iPop, rho, u, uSqr, vs2);
}
template<typename T, typename DESCRIPTOR>
void ChopardDynamics<T,DESCRIPTOR>::collide (
Cell<T,DESCRIPTOR>& cell,
LatticeStatistics<T>& statistics )
{
T rho, u[DESCRIPTOR::d];
this->_momenta.computeRhoU(cell, rho, u);
T uSqr = chopardBgkCollision(cell, rho, u, vs2, omega);
statistics.incrementStats(rho, uSqr);
}
template<typename T, typename DESCRIPTOR>
T ChopardDynamics<T,DESCRIPTOR>::getOmega() const
{
return omega;
}
template<typename T, typename DESCRIPTOR>
void ChopardDynamics<T,DESCRIPTOR>::setOmega(T omega_)
{
omega = omega_;
}
template<typename T, typename DESCRIPTOR>
T ChopardDynamics<T,DESCRIPTOR>::getVs2() const
{
return vs2;
}
template<typename T, typename DESCRIPTOR>
void ChopardDynamics<T,DESCRIPTOR>::setVs2(T vs2_)
{
vs2 = vs2_;
}
template<typename T, typename DESCRIPTOR>
T ChopardDynamics<T,DESCRIPTOR>::chopardBgkCollision (
Cell<T,DESCRIPTOR>& cell, T rho, const T u[DESCRIPTOR::d], T vs2, T omega)
{
const T uSqr = util::normSqr<T,DESCRIPTOR::d>(u);
for (int iPop=0; iPop < DESCRIPTOR::q; ++iPop) {
cell[iPop] *= (T)1-omega;
cell[iPop] += omega * chopardEquilibrium(iPop, rho, u, uSqr, vs2);
}
return uSqr;
}
template<typename T, typename DESCRIPTOR>
T ChopardDynamics<T,DESCRIPTOR>::chopardEquilibrium (
int iPop, T rho, const T u[DESCRIPTOR::d], T uSqr, T vs2)
{
if (iPop==0) {
return rho*( (T)1 -
vs2*descriptors::invCs2<T,DESCRIPTOR>()*((T)1-descriptors::t<T,DESCRIPTOR>(0)) -
descriptors::t<T,DESCRIPTOR>(0)/(T)2*descriptors::invCs2<T,DESCRIPTOR>()*uSqr ) - descriptors::t<T,DESCRIPTOR>(0);
} else {
T c_u = T();
for (int iD=0; iD < DESCRIPTOR::d; ++iD) {
c_u += descriptors::c<DESCRIPTOR>(iPop,iD)*u[iD];
}
return rho * descriptors::t<T,DESCRIPTOR>(iPop) * descriptors::invCs2<T,DESCRIPTOR>()* (
vs2 + c_u +
descriptors::invCs2<T,DESCRIPTOR>() / (T)2 * c_u*c_u -
uSqr / (T)2
) - descriptors::t<T,DESCRIPTOR>(iPop);
}
}
}
#endif
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