From 94d3e79a8617f88dc0219cfdeedfa3147833719d Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Mon, 24 Jun 2019 14:43:36 +0200
Subject: Initialize at openlb-1-3

---
 src/dynamics/guoZhaoLbHelpers.h | 166 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 166 insertions(+)
 create mode 100644 src/dynamics/guoZhaoLbHelpers.h

(limited to 'src/dynamics/guoZhaoLbHelpers.h')

diff --git a/src/dynamics/guoZhaoLbHelpers.h b/src/dynamics/guoZhaoLbHelpers.h
new file mode 100644
index 0000000..683ad93
--- /dev/null
+++ b/src/dynamics/guoZhaoLbHelpers.h
@@ -0,0 +1,166 @@
+/*  This file is part of the OpenLB library
+ *
+ *  Copyright (C) 2016-2017 Davide Dapelo, Mathias J. Krause
+ *  OpenLB 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
+ * Helper functions for the implementation of the
+ * Guo-ZhapLB dynamics.
+ */
+
+#ifndef LB_GUOZHAO_HELPERS_H
+#define LB_GUOZHAO_HELPERS_H
+
+#include "dynamics/guoZhaoLatticeDescriptors.h"
+#include "core/cell.h"
+#include "core/util.h"
+
+
+namespace olb {
+
+
+// Forward declarations
+template<typename T, typename DESCRIPTORBASE> struct GuoZhaoLbDynamicsHelpers;
+template<typename T, typename DESCRIPTOR> struct GuoZhaoLbExternalHelpers;
+
+/// This structure forwards the calls to the appropriate Guo Zhao helper class
+template<typename T, typename DESCRIPTOR>
+struct GuoZhaoLbHelpers {
+
+  static T equilibrium(int iPop, T epsilon, T rho, const T u[DESCRIPTOR::d], const T uSqr) {
+    return GuoZhaoLbDynamicsHelpers<T,typename DESCRIPTOR::BaseDescriptor>
+           ::equilibrium(iPop, epsilon, rho, u, uSqr);
+  }
+
+  static T bgkCollision(Cell<T,DESCRIPTOR>& cell, T const& epsilon, T const& rho, const T u[DESCRIPTOR::d], T const& omega) {
+    return GuoZhaoLbDynamicsHelpers<T,typename DESCRIPTOR::BaseDescriptor>
+           ::bgkCollision(cell, epsilon, rho, u, omega);
+  }
+
+  static void updateGuoZhaoForce(Cell<T,DESCRIPTOR>& cell, const T u[DESCRIPTOR::d]) {
+    GuoZhaoLbExternalHelpers<T,DESCRIPTOR>::updateGuoZhaoForce(cell, u);
+  }
+
+  static void addExternalForce(Cell<T,DESCRIPTOR>& cell, const T u[DESCRIPTOR::d], T omega, T rho, T epsilon=(T)1)
+  {
+    GuoZhaoLbExternalHelpers<T,DESCRIPTOR>::addExternalForce(cell, u, omega, rho, epsilon);
+  }
+
+};  // struct GuoZhaoLbHelpers
+
+
+/// All Guo Zhao helper functions are inside this structure
+template<typename T, typename DESCRIPTORBASE>
+struct GuoZhaoLbDynamicsHelpers {
+
+  /// Computation of Guo Zhao equilibrium distribution - original (compressible) formulation following Guo and Zhao (2002).
+  static T forceEquilibrium(int iPop, T epsilon, T rho, const T u[DESCRIPTORBASE::d], const T force[DESCRIPTORBASE::d], T nu) {
+  }
+
+  /// Computation of Guo Zhao equilibrium distribution - original (compressible) formulation following Guo and Zhao (2002).
+  static T equilibrium(int iPop, T epsilon, T rho, const T u[DESCRIPTORBASE::d], const T uSqr) {
+    T c_u = T();
+    for (int iD=0; iD < DESCRIPTORBASE::d; ++iD) {
+      c_u += descriptors::c<DESCRIPTORBASE>(iPop,iD)*u[iD];
+    }
+    return rho * descriptors::t<T,DESCRIPTORBASE>(iPop) * (
+             (T)1 + descriptors::invCs2<T,DESCRIPTORBASE>() * c_u +
+             descriptors::invCs2<T,DESCRIPTORBASE>() * descriptors::invCs2<T,DESCRIPTORBASE>()/((T)2*epsilon) * c_u*c_u -
+             descriptors::invCs2<T,DESCRIPTORBASE>()/((T)2*epsilon) * uSqr
+           ) - descriptors::t<T,DESCRIPTORBASE>(iPop);
+  }
+
+  /// Guo Zhao BGK collision step
+  static T bgkCollision(CellBase<T,DESCRIPTORBASE>& cell, T const& epsilon, T const& rho, const T u[DESCRIPTORBASE::d], T const& omega) {
+    const T uSqr = util::normSqr<T,DESCRIPTORBASE::d>(u);
+    for (int iPop=0; iPop < DESCRIPTORBASE::q; ++iPop) {
+      cell[iPop] *= (T)1-omega;
+      cell[iPop] += omega * GuoZhaoLbDynamicsHelpers<T,DESCRIPTORBASE>::equilibrium (
+                      iPop, epsilon, rho, u, uSqr );
+    }
+    return uSqr;
+  }
+
+};  // struct GuoZhaoLbDynamicsHelpers
+
+/// Helper functions for dynamics that access external field
+template<typename T, typename DESCRIPTOR>
+/// Updates Guo Zhao porous force
+struct GuoZhaoLbExternalHelpers {
+  static void updateGuoZhaoForce(Cell<T,DESCRIPTOR>& cell, const T u[DESCRIPTOR::d]) {
+    T epsilon = *cell.template getFieldPointer<descriptors::EPSILON>();
+    T k       = *cell.template getFieldPointer<descriptors::K>();
+    T nu      = *cell.template getFieldPointer<descriptors::NU>();
+
+    T* force[DESCRIPTOR::d];
+    for (int iDim=0; iDim <DESCRIPTOR::d; iDim++) {
+      force[iDim] = cell.template getFieldPointer<descriptors::FORCE>() + iDim;
+    }
+
+    T bodyF[DESCRIPTOR::d];
+    for (int iDim=0; iDim <DESCRIPTOR::d; iDim++) {
+      bodyF[iDim] = cell.template getFieldPointer<descriptors::BODY_FORCE>()[iDim];
+    }
+
+    T uMag = 0.;
+    for (int iDim=0; iDim <DESCRIPTOR::d; iDim++) {
+      uMag += u[iDim]*u[iDim];
+    }
+    uMag = sqrt(uMag);
+
+    T Fe = 0.; //1.75/sqrt(150.*pow(epsilon,3));
+
+    // Linear Darcy term, nonlinear Forchheimer term and body force
+    for (int iDim=0; iDim <DESCRIPTOR::d; iDim++) {
+      *force[iDim] = -u[iDim]*epsilon*nu/k - epsilon*Fe/sqrt(k)*uMag*u[iDim] + bodyF[iDim]*epsilon;
+    }
+  }
+
+  /// Add a force term scaled by physical porosity epsilon after BGK collision
+  static void addExternalForce(Cell<T,DESCRIPTOR>& cell, const T u[DESCRIPTOR::d], T omega, T rho, T epsilon)
+  {
+    T* force = cell.template getFieldPointer<descriptors::FORCE>();
+    for (int iPop=0; iPop < DESCRIPTOR::q; ++iPop) {
+      T c_u = T();
+      for (int iD=0; iD < DESCRIPTOR::d; ++iD) {
+        c_u += descriptors::c<DESCRIPTOR>(iPop,iD)*u[iD];
+      }
+      c_u *= descriptors::invCs2<T,DESCRIPTOR>()*descriptors::invCs2<T,DESCRIPTOR>()/epsilon;
+      T forceTerm = T();
+      for (int iD=0; iD < DESCRIPTOR::d; ++iD) {
+        forceTerm +=
+          (   (epsilon*(T)descriptors::c<DESCRIPTOR>(iPop,iD)-u[iD]) * descriptors::invCs2<T,DESCRIPTOR>()/epsilon
+              + c_u * descriptors::c<DESCRIPTOR>(iPop,iD)
+          )
+          * force[iD];
+      }
+      forceTerm *= descriptors::t<T,DESCRIPTOR>(iPop);
+      forceTerm *= T(1) - omega/T(2);
+      forceTerm *= rho;
+      cell[iPop] += forceTerm;
+    }
+  }
+};  // struct GuoZhaoLbExternalHelpers
+
+}  // namespace olb
+
+
+#endif
-- 
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