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/* This file is part of the OpenLB library
*
* Copyright (C) 2013 Patrick Nathen
* 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
* MRT Dynamics with adjusted omega -- header file.
*/
#ifndef STOCHASTIC_SGS_DYNAMICS_H
#define STOCHASTIC_SGS_DYNAMICS_H
#include "mrtDynamics.h"
#include "core/cell.h"
namespace olb {
/// Implementation of the MRT collision step with stochastic relaxation based on
/// " A stochastic subgrid model with application to turbulent flow and scalar mixing"; Phys. of Fluids 19; 2007
template<typename T, typename DESCRIPTOR>
class StochasticSGSdynamics : public MRTdynamics<T,DESCRIPTOR> {
public:
/// Constructor
StochasticSGSdynamics(T omega_, Momenta<T,DESCRIPTOR>& momenta_, T turbulenceInt_, T charU_, T smagoConst_, T dx_ = 1, T dt_ = 1 );
// Collide
virtual void collide(Cell<T,DESCRIPTOR>& cell,
LatticeStatistics<T>& statistics_);
/// Set local relaxation parameter of the dynamics
virtual void setOmega(T omega_);
/// Get local smagorinsky relaxation parameter of the dynamics
virtual T getSmagorinskyOmega(Cell<T,DESCRIPTOR>& cell_, T X_lang_n_);
/// Get local Random number of BoxMüllertransform -> returns randBM
virtual T getRandBMTrans(Cell<T,DESCRIPTOR>& cell_, T turbulenceInt_, T charU_);
/// Get local Random number of BoxMüllertransform -> returns randBM
// virtual void setRandomWalk(Cell<T,DESCRIPTOR>& cell_, T CharU, T drift_, T result_ );
virtual T getRandomWalk(Cell<T,DESCRIPTOR>& cell_, T drift_, T result_);
private:
/// Computes a constant prefactor in order to speed up the computation
T computePreFactor(T omega_, T smagoConst_);
/// Computes the local smagorinsky relaxation parameter
T computeOmega(T omega0_, T preFactor_, T rho_, T pi_[util::TensorVal<DESCRIPTOR >::n] , T X_lang_n_);
/// Computes the local time scale from SGS dissipation rate for BMtransform
T computeTimeScale(T preFactor_, T rho_, T pi_[util::TensorVal<DESCRIPTOR >::n], T smagoConst_, T X_lang_n_);
// virtual void setTimeScale(T preFactor_, T rho_, T pi_[util::TensorVal<DESCRIPTOR >::n], T smagoConst_ ,T X_lang_n_);
private:
/// effective collision time based upon Smagorisnky approach
T tau_eff;
/// Initial turbulence intensity for random number generator
T turbulenceInt;
/// Smagorinsky Constant
/// Precomputed constant which speeeds up the computation
T smagoConst;
T preFactor;
T dx;
T dt;
T omega; // the shear viscosity relaxatin time
T lambda;// the bulk viscosity relaxatin time
//T result;
T charU;
//T drift;
T X_lang_n;
// Relaxation Time Matrix for
T invM_S_SGS[DESCRIPTOR::q][DESCRIPTOR::q];
};
}
#endif
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