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diff --git a/src/dynamics/stochasticSGSdynamics.hh b/src/dynamics/stochasticSGSdynamics.hh new file mode 100644 index 0000000..b61958f --- /dev/null +++ b/src/dynamics/stochasticSGSdynamics.hh @@ -0,0 +1,293 @@ +/* This file is part of the OpenLB library + * + * Copyright (C) 2013 Mathias J. Krause, 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 + * MRT Dynamics with adjusted omega -- generic implementation. + */ +#ifndef STOCHASTIC_SGS_DYNAMICS_HH +#define STOCHASTIC_SGS_DYNAMICS_HH + +#include <algorithm> +#include <limits> +#include "stochasticSGSdynamics.h" +#include "mrtDynamics.h" +#include "mrtHelpers.h" +#include "core/cell.h" +#include "core/util.h" +#include "math.h" + +#include <stdlib.h> +#include <math.h> +#include <time.h> +#include <stdio.h> + + +using namespace std; +namespace olb { + +/// Implementation of the Stochastic relaxation based on +/// " A stochastic subgrid model with application to turbulent flow and scalar mixing"; Phys. of Fluids 19; 2007 + +////////////////////// Class StochasticsSGSdynamics ////////////////////////// + +/** \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> +StochasticSGSdynamics<T,DESCRIPTOR>::StochasticSGSdynamics ( + T omega_, Momenta<T,DESCRIPTOR>& momenta_, T turbulenceInt_, T charU_, T smagoConst_, T dx_, T dt_) + : MRTdynamics<T,DESCRIPTOR>(omega_, momenta_), + turbulenceInt(turbulenceInt_), + smagoConst(smagoConst_), + charU(charU_), + preFactor(computePreFactor(omega_,smagoConst_) ) + +{ + + // T invM_S_SGS[DESCRIPTOR::q][DESCRIPTOR::q]; + // T rtSGS[DESCRIPTOR::q]; // relaxation times vector for SGS approach. + // for (int iPop = 0; iPop < DESCRIPTOR::q; ++iPop) + // { + // rtSGS[iPop] = DESCRIPTOR::S[iPop]; + // } + // for (int iPop = 0; iPop < DESCRIPTOR::shearIndexes; ++iPop) + // { + // rtSGS[DESCRIPTOR::shearViscIndexes[iPop]] = omega; + // } + // for (int iPop = 0; iPop < DESCRIPTOR::q; ++iPop) + // { + // for (int jPop = 0; jPop < DESCRIPTOR::q; ++jPop) + // { + // invM_S_SGS[iPop][jPop] = T(); + // for (int kPop = 0; kPop < DESCRIPTOR::q; ++kPop) + // { + // if (kPop == jPop) + // { + // invM_S_SGS[iPop][jPop] += DESCRIPTOR::invM[iPop][kPop] * + // rtSGS[kPop]; + // cout << "wert"<<iPop <<jPop << "= "<< invM_S_SGS[iPop][jPop]<< endl; + // } + // } + // } + // } + // + + +} + + +template<typename T, typename DESCRIPTOR> +void StochasticSGSdynamics<T,DESCRIPTOR>::collide( + Cell<T,DESCRIPTOR>& cell, + LatticeStatistics<T>& statistics ) +{ + T rho, u[DESCRIPTOR::d], pi[util::TensorVal<DESCRIPTOR >::n]; + + + + T drift = computeTimeScale(preFactor, rho, pi, smagoConst, X_lang_n); + T result = getRandBMTrans(cell, turbulenceInt, charU); + + // cout << "vor neu setzen: "<<X_lang_n<< endl; + X_lang_n = getRandomWalk(cell, drift, result); + // cout << "nach neu setzen: "<<X_lang_n<< endl; + //cout << X_lang_n<< endl; + // cout << drift<< endl; + // cout << result<< endl; + + + this->_momenta.computeAllMomenta(cell, rho, u, pi); + T newOmega = computeOmega(this->getOmega(), preFactor, rho, pi, X_lang_n); + + + T invM_S_SGS[DESCRIPTOR::q][DESCRIPTOR::q]; + T rtSGS[DESCRIPTOR::q]; // relaxation times vector for SGS approach. + for (int iPop = 0; iPop < DESCRIPTOR::q; ++iPop) { + rtSGS[iPop] = DESCRIPTOR::S[iPop]; + } + for (int iPop = 0; iPop < DESCRIPTOR::shearIndexes; ++iPop) { + rtSGS[DESCRIPTOR::shearViscIndexes[iPop]] = newOmega; + } + for (int iPop = 0; iPop < DESCRIPTOR::q; ++iPop) { + for (int jPop = 0; jPop < DESCRIPTOR::q; ++jPop) { + invM_S_SGS[iPop][jPop] = T(); + for (int kPop = 0; kPop < DESCRIPTOR::q; ++kPop) { + if (kPop == jPop) { + invM_S_SGS[iPop][jPop] += DESCRIPTOR::invM[iPop][kPop] * + rtSGS[kPop]; + //cout << "wert"<<iPop <<jPop << "= "<< invM_S_SGS[iPop][jPop]<< endl; + } + } + } + } + + T uSqr = mrtHelpers<T,DESCRIPTOR>::mrtSGSCollision(cell, rho, u, newOmega, invM_S_SGS); + statistics.incrementStats(rho, uSqr); +} + +template<typename T, typename DESCRIPTOR> +void StochasticSGSdynamics<T,DESCRIPTOR>::setOmega(T omega) +{ + this->setOmega(omega); + preFactor = computePreFactor(omega, smagoConst); +} + +template<typename T, typename DESCRIPTOR> +T StochasticSGSdynamics<T,DESCRIPTOR>::getSmagorinskyOmega(Cell<T,DESCRIPTOR>& cell, T X_lang_n ) +{ + T rho, uTemp[DESCRIPTOR::d], pi[util::TensorVal<DESCRIPTOR >::n]; + this->_momenta.computeAllMomenta(cell, rho, uTemp, pi); + T newOmega = computeOmega(this->getOmega(), preFactor, rho, pi, X_lang_n); + return newOmega; +} + + + +template<typename T, typename DESCRIPTOR> +T StochasticSGSdynamics<T,DESCRIPTOR>::getRandBMTrans( + Cell<T,DESCRIPTOR>& cell, + T turbulenceInt, T CharU ) +{ + /// Random number generator based on Box Müller transform to produuce random normal + /// distributed numbers with zero mean and + + T mean = 0.; + T TKE_ini = 1.5*turbulenceInt*turbulenceInt*charU*charU; + T velStDev = sqrt(2./3.*TKE_ini); + static double n2 = 0.0; + static int n2_cached = 0; + if (!n2_cached) { + double x, y, r; + do { + x = 2.0*rand()/RAND_MAX - 1; + y = 2.0*rand()/RAND_MAX - 1; + + r = x*x + y*y; + } while ( util::nearZero(r) || r > 1.0); + { + double d = sqrt(-2.0*log(r)/r); + double n1 = x*d; + n2 = y*d; + double result = n1*velStDev + mean; + n2_cached = 1; + return result; + } + } else { + n2_cached = 0; + return n2*velStDev + mean; + } +} + + +/// Create Random walk +template<typename T, typename DESCRIPTOR> +T StochasticSGSdynamics<T,DESCRIPTOR>::getRandomWalk( + Cell<T,DESCRIPTOR>& cell, + T drift, T result) +{ + /// initialisation of model standard variation, see Pope pp 484 + T sigma = 2.3; + X_lang_n *=drift; + + X_lang_n += sigma*sqrt(drift*2)*result; + + return X_lang_n; + + +} +/// set random walk + +// template<typename T, typename DESCRIPTOR> +// void StochasticSGSdynamics<T,DESCRIPTOR>::setRandomWalk( +// Cell<T,DESCRIPTOR>& cell, +// T CharU, T drift, T result ) +// { +// /// initialisation of model standard variation, see Pope pp 484 +// T X_lang_n = getRandomWalk(cell, CharU, drift, result); +// } + + +// /// get time sclae +template<typename T, typename DESCRIPTOR> +T StochasticSGSdynamics<T,DESCRIPTOR>::computeTimeScale( + T preFactor, T rho, T pi[util::TensorVal<DESCRIPTOR >::n], T smagoConst, T X_lang_n ) +{ + T Const = 0.2; + T PiNeqNormSqr = pi[0]*pi[0] + 2.0*pi[1]*pi[1] + pi[2]*pi[2]; + if (util::TensorVal<DESCRIPTOR >::n == 6) { + PiNeqNormSqr += pi[2]*pi[2] + pi[3]*pi[3] + 2*pi[4]*pi[4] +pi[5]*pi[5]; + } + T PiNeqNorm = sqrt(PiNeqNormSqr); + + /// SGS dissipation is calcualted directly withou any filter size due to effeiciency in tau + // for post processing this has to be evaluated seperately with S_ij³ + T diss_corr = smagoConst*smagoConst*PiNeqNorm*PiNeqNorm*PiNeqNorm*(1+ X_lang_n); + + T tau= Const*pow(( 1. / diss_corr ), 1./3.); + T drift = 1./tau; + /// deterministic drift time scale T_L see Pope pp. 484 + return drift; + +} + + +// // // /// set timescale +// template<typename T, typename DESCRIPTOR> +// void StochasticSGSdynamics<T,DESCRIPTOR>::setTimeScale( +// T preFactor, T rho, T pi[util::TensorVal<DESCRIPTOR >::n], T smagoConst, T X_lang_n) +// { +// T drift = computeTimeScale(preFactor, rho, pi, smagoConst, X_lang_n); +// } + + +template<typename T, typename DESCRIPTOR> +T StochasticSGSdynamics<T,DESCRIPTOR>::computePreFactor(T omega, T smagoConst) +{ + return (T)smagoConst*smagoConst*descriptors::invCs2<T,DESCRIPTOR>()*descriptors::invCs2<T,DESCRIPTOR>()*2*sqrt(2); +} + +template<typename T, typename DESCRIPTOR> +T StochasticSGSdynamics<T,DESCRIPTOR>::computeOmega(T omega0, T preFactor, T rho, T pi[util::TensorVal<DESCRIPTOR >::n], T X_lang_n) +{ + T PiNeqNormSqr = pi[0]*pi[0] + 2.0*pi[1]*pi[1] + pi[2]*pi[2]; + if (util::TensorVal<DESCRIPTOR >::n == 6) { + PiNeqNormSqr += pi[2]*pi[2] + pi[3]*pi[3] + 2*pi[4]*pi[4] +pi[5]*pi[5]; + } + T PiNeqNorm = sqrt(PiNeqNormSqr); + /// Molecular realaxation time + T tau_mol = 1. /omega0; + /// Turbulent realaxation time + T tau_turb = 0.5*(sqrt(tau_mol*tau_mol+(preFactor*tau_eff*PiNeqNorm*(1+X_lang_n)))-tau_mol); + /// Effective realaxation time + tau_eff = tau_mol+tau_turb; + T omega_new= 1./tau_eff; + return omega_new; +} + +} + +#endif |