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/* This file is part of the OpenLB library
*
* Copyright (C) 2012, 2015 Mathias J. Krause, Vojtech Cvrcekt, Davide Dapelo
* 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 adjusted omega -- generic implementation.
* Strain rate similar to "J.Boyd, J. Buick and S.Green: A second-order accurate lattice Boltzmann non-Newtonian flow model"
* Power Law similar to "Huidan Yu, Sharath S. Girimaji, Li-Shi Luo - DNS and LES of decaying isotropic turbulence with and without frame rotation using lattice Boltzmann method"
*/
#ifndef POWER_LAW_BGK_DYNAMICS_HH
#define POWER_LAW_BGK_DYNAMICS_HH
#include "dynOmegaLatticeDescriptors.h"
#include "powerLawBGKdynamics.h"
#include "core/cell.h"
#include "core/util.h"
#include "lbHelpers.h"
#include "latticeDescriptors.h"
#include "math.h"
namespace olb {
////////////////////// Class PowerLawDynamics //////////////////////////
template<typename T, typename DESCRIPTOR>
PowerLawDynamics<T,DESCRIPTOR>::PowerLawDynamics (T m, T n , T nuMin, T nuMax)
: _m(m),
_n(n)
{
_omegaMin = 2./(nuMax*2.*descriptors::invCs2<T,DESCRIPTOR>() + 1.);
_omegaMax = 2./(nuMin*2.*descriptors::invCs2<T,DESCRIPTOR>() + 1.);
}
template<typename T, typename DESCRIPTOR>
T PowerLawDynamics<T,DESCRIPTOR>::computeOmegaPL( Cell<T,DESCRIPTOR>& cell, T omega0,
T rho, T pi[util::TensorVal<DESCRIPTOR >::n] )
{
T pre2 = pow(descriptors::invCs2<T,DESCRIPTOR>()/2.* omega0/rho,2.); // strain rate tensor prefactor
T gamma = sqrt(2.*pre2*PiNeqNormSqr(cell)); // shear rate
T nuNew = _m*pow(gamma,_n-1.); //nu for non-Newtonian fluid
T newOmega = 2./(nuNew*2.*descriptors::invCs2<T,DESCRIPTOR>() + 1.);
if (newOmega>_omegaMax) {
newOmega = _omegaMax;
}
if (newOmega<_omegaMin) {
newOmega = _omegaMin;
}
return newOmega;
}
////////////////////// Class PowerLawBGKdynamics //////////////////////////
/** \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>
PowerLawBGKdynamics<T,DESCRIPTOR>::PowerLawBGKdynamics (
T omega, Momenta<T,DESCRIPTOR>& momenta, T m, T n , T nuMin, T nuMax)
: BGKdynamics<T,DESCRIPTOR>(omega, momenta),
PowerLawDynamics<T,DESCRIPTOR>(m, n, nuMin, nuMax)
{ }
template<typename T, typename DESCRIPTOR>
void PowerLawBGKdynamics<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);
// Computation of the power-law omega.
// An external is used in place of BGKdynamics::_omega to keep generality and flexibility.
const auto oldOmega = cell.template getField<descriptors::OMEGA>();
const auto newOmega = this->computeOmegaPL(cell, oldOmega, rho, pi);
const T uSqr = lbHelpers<T,DESCRIPTOR>::bgkCollision(cell, rho, u, newOmega);
cell.template setField<descriptors::OMEGA>(newOmega);
statistics.incrementStats(rho, uSqr);
}
template<typename T, typename DESCRIPTOR>
T PowerLawBGKdynamics<T,DESCRIPTOR>::PiNeqNormSqr(Cell<T,DESCRIPTOR>& cell )
{
return lbHelpers<T,DESCRIPTOR>::computePiNeqNormSqr(cell);
}
////////////////////// Class ForcedPowerLawBGKdynamics //////////////////////////
/** \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>
PowerLawForcedBGKdynamics<T,DESCRIPTOR>::PowerLawForcedBGKdynamics (
T omega, Momenta<T,DESCRIPTOR>& momenta, T m, T n , T nuMin, T nuMax)
: ForcedBGKdynamics<T,DESCRIPTOR>(omega, momenta),
PowerLawDynamics<T,DESCRIPTOR>(m, n, nuMin, nuMax)
{ }
template<typename T, typename DESCRIPTOR>
void PowerLawForcedBGKdynamics<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);
// Computation of the power-law omega.
// An external is used in place of BGKdynamics::_omega to keep generality and flexibility.
T oldOmega = cell.template getFieldPointer<descriptors::OMEGA>()[0];
T newOmega = this->computeOmegaPL(cell, oldOmega, 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 = lbHelpers<T,DESCRIPTOR>::bgkCollision(cell, rho, u, this->getOmega());
lbHelpers<T,DESCRIPTOR>::addExternalForce(cell, u, newOmega, rho);
cell.template getFieldPointer<descriptors::OMEGA>()[0] = newOmega; // updating omega
statistics.incrementStats(rho, uSqr);
}
template<typename T, typename DESCRIPTOR>
T PowerLawForcedBGKdynamics<T,DESCRIPTOR>::PiNeqNormSqr(Cell<T,DESCRIPTOR>& cell )
{
return lbHelpers<T,DESCRIPTOR>::computeForcedPiNeqNormSqr(cell);
}
}
#endif
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