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/* This file is part of the OpenLB library
*
* Copyright (C) 2006, 2007, 2017 Orestis Malaspinas, Jonas Latt, 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
* A collection of entropic dynamics classes (e.g. EntropicEq,
* ForcedEntropicEq, Entropic, ForcedEntropic) with which a Cell object
* can be instantiated -- header file.
*
* Entropic Modell:
* Ansumali, Santosh, Iliya V. Karlin, and Hans Christian Öttinger
* Minimal entropic kinetic models for hydrodynamics
* EPL (Europhysics Letters) 63.6 (2003): 798
*/
#ifndef ENTROPIC_LB_DYNAMICS_H
#define ENTROPIC_LB_DYNAMICS_H
#include "dynamics/dynamics.h"
namespace olb {
template<typename T, typename DESCRIPTOR> class Cell;
/// Implementation of the entropic collision step
template<typename T, typename DESCRIPTOR>
class EntropicEqDynamics : public BasicDynamics<T,DESCRIPTOR> {
public:
/// Constructor
EntropicEqDynamics(T omega_, Momenta<T,DESCRIPTOR>& momenta_);
/// Compute equilibrium distribution function
T computeEquilibrium(int iPop, T rho, const T u[DESCRIPTOR::d], T uSqr) const override;
/// Collision step
void collide(Cell<T,DESCRIPTOR>& cell,
LatticeStatistics<T>& statistics_) override;
/// Get local relaxation parameter of the dynamics
T getOmega() const override;
/// Set local relaxation parameter of the dynamics
void setOmega(T omega_) override;
private:
T omega; ///< relaxation parameter
};
/// Implementation of the forced entropic collision step
template<typename T, typename DESCRIPTOR>
class ForcedEntropicEqDynamics : public BasicDynamics<T,DESCRIPTOR> {
public:
/// Constructor
ForcedEntropicEqDynamics(T omega_, Momenta<T,DESCRIPTOR>& momenta_);
/// Compute equilibrium distribution function
virtual T computeEquilibrium(int iPop, T rho, const T u[DESCRIPTOR::d], T uSqr) const;
/// Collision step
virtual void collide(Cell<T,DESCRIPTOR>& cell,
LatticeStatistics<T>& statistics_);
/// Get local relaxation parameter of the dynamics
virtual T getOmega() const;
/// Set local relaxation parameter of the dynamics
virtual void setOmega(T omega_);
private:
T omega; ///< relaxation parameter
};
/// Implementation of the entropic collision step
template<typename T, typename DESCRIPTOR>
class EntropicDynamics : public BasicDynamics<T,DESCRIPTOR> {
public:
/// Constructor
EntropicDynamics(T omega_, Momenta<T,DESCRIPTOR>& momenta_);
/// Compute equilibrium distribution function
T computeEquilibrium(int iPop, T rho, const T u[DESCRIPTOR::d], T uSqr) const override;
/// Collision step
void collide(Cell<T,DESCRIPTOR>& cell,
LatticeStatistics<T>& statistics_) override;
/// Get local relaxation parameter of the dynamics
T getOmega() const override;
/// Set local relaxation parameter of the dynamics
void setOmega(T omega_) override;
private:
/// computes the entropy function H(f)=sum_i f_i*ln(f_i/t_i)
T computeEntropy(const T f[]);
/// computes the entropy growth H(f)-H(f-alpha*fNeq)
T computeEntropyGrowth(const T f[], const T fNeq[], const T &alpha);
/// computes the entropy growth derivative
/// dH/dalpha=-sum_i fNeq_i*ln((f_i-alpha*fNeq_i)/t_i)
T computeEntropyGrowthDerivative(const T f[], const T fNeq[], const T &alpha);
/// Get the alpha parameter
bool getAlpha(T &alpha, const T f[], const T fNeq[]);
T omega; ///< relaxation parameter
};
/// Implementation of the forced entropic collision step
template<typename T, typename DESCRIPTOR>
class ForcedEntropicDynamics : public BasicDynamics<T,DESCRIPTOR> {
public:
/// Constructor
ForcedEntropicDynamics(T omega_, Momenta<T,DESCRIPTOR>& momenta_);
/// Compute equilibrium distribution function
virtual T computeEquilibrium(int iPop, T rho, const T u[DESCRIPTOR::d], T uSqr) const;
/// Collision step
virtual void collide(Cell<T,DESCRIPTOR>& cell,
LatticeStatistics<T>& statistics_);
/// Get local relaxation parameter of the dynamics
virtual T getOmega() const;
/// Set local relaxation parameter of the dynamics
virtual void setOmega(T omega_);
private:
/// computes the entropy function H(f)=sum_i f_i*ln(f_i/t_i)
T computeEntropy(const T f[]);
/// computes the entropy growth H(f)-H(f-alpha*fNeq)
T computeEntropyGrowth(const T f[], const T fNeq[], const T &alpha);
/// computes the entropy growth derivative
/// dH/dalpha=-sum_i fNeq_i*ln((f_i-alpha*fNeq_i)/t_i)
T computeEntropyGrowthDerivative(const T f[], const T fNeq[], const T &alpha);
/// Get the alpha parameter
bool getAlpha(T &alpha, const T f[], const T fNeq[]);
T omega; ///< relaxation parameter
};
}
#endif
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