Initialize at openlb-1-3

1 files changed, 106 insertions, 0 deletions

diff --git a/src/dynamics/entropicLbHelpers3D.h b/src/dynamics/entropicLbHelpers3D.h
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+++ b/src/dynamics/entropicLbHelpers3D.h
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+/*  This file is part of the OpenLB library
+ *
+ *  Copyright (C) 2006, 2007 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
+ * A collection of dynamics classes (e.g. BGK) with which a Cell object
+ * can be instantiated -- header file.
+ */
+#ifndef ENTROPIC_LB_HELPERS_3D_H
+#define ENTROPIC_LB_HELPERS_3D_H
+
+#include <cmath>
+
+namespace olb {
+
+template<typename T>
+struct entropicLbHelpers<T, descriptors::D3Q19<>> {
+  /// Computation of equilibrium distribution with an expansion
+  /// with respect to a small velocity u
+  static T equilibrium( int iPop, T rho, const T u[3])
+  {
+    typedef descriptors::D3Q19<> L;
+
+    T c_u = descriptors::c<L>(iPop,0)*u[0] + descriptors::c<L>(iPop,1)*u[1] + descriptors::c<L>(iPop,2)*u[2];;
+    T c_u2 = c_u*c_u;
+    T c_u3 = c_u2*c_u;
+    T c_u4 = c_u3*c_u;
+    T c_u5 = c_u4*c_u;
+    T c_u6 = c_u5*c_u;
+    T c_u7 = c_u6*c_u;
+
+    T uSqr = u[0]*u[0] + u[1]*u[1] + u[2]*u[2];
+    T uSqr2 = uSqr*uSqr;
+    T uSqr3 = uSqr2*uSqr;
+
+    T powUx = u[0]*u[0]*u[0]*u[0]*u[0]; // u_x^5
+    T powUy = u[1]*u[1]*u[1]*u[1]*u[1]; // u_y^5
+    T powUz = u[2]*u[2]*u[2]*u[2]*u[2]; // u_z^5
+
+    T C = descriptors::c<L>(iPop,0) * powUx + descriptors::c<L>(iPop,1) * powUy
+          + descriptors::c<L>(iPop,2) * powUz;
+
+    powUx *= u[0]; // u_x^6
+    powUy *= u[1]; // u_y^6
+    powUz *= u[2]; // u_z^6
+
+    T E = powUx + powUy + powUz;
+
+    powUx *= u[0]; // u_x^7
+    powUy *= u[1]; // u_y^7
+    powUz *= u[2]; // u_z^7
+
+    T F = descriptors::c<L>(iPop,0) * powUx + descriptors::c<L>(iPop,1) * powUy + descriptors::c<L>(iPop,2) * powUz;
+
+    return descriptors::t<T,L>(iPop) * rho *
+           ((T)1
+            + c_u*(C*(T)81/(T)20 + uSqr2*(T)27/(T)8 - uSqr*(T)9/(T)2
+                   - E*(T)81/(T)24 - uSqr3*(T)81/(T)48 + (T)3)
+
+            + c_u2*(uSqr2*(T)81/(T)16 - uSqr*(T)27/(T)4
+                    + C*(T)243/(T)40 + (T)9/(T)2)
+
+            + c_u3*(uSqr2*(T)243/(T)48 - uSqr*(T)81/(T)12 + (T)27/(T)6)
+
+            - c_u4*uSqr*(T)243/(T)48
+            + c_u4*(T)81/(T)24
+
+            - c_u5*uSqr*(T)729/(T)240
+            + c_u5*(T)243/(T)120
+
+            + c_u6*(T)729/(T)720
+
+            + c_u7*(T)2187/(T)5040
+
+            - C*uSqr*(T)81/(T)40
+
+            + C*(T)27/(T)20 - uSqr3*(T)27/(T)48 - E*(T)27/(T)24
+            - F*(T)81/(T)56 - uSqr*(T)3/(T)2 + uSqr2*(T)9/(T)8
+           )
+           - descriptors::t<T,L>(iPop);
+  }
+
+};
+
+}
+
+#endif