Initialize at openlb-1-3

1 files changed, 229 insertions, 0 deletions

diff --git a/src/dynamics/mrtHelpers2D.h b/src/dynamics/mrtHelpers2D.h
new file mode 100644
index 0000000..1d6b889
--- /dev/null
+++ b/src/dynamics/mrtHelpers2D.h
@@ -0,0 +1,229 @@
+/*  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
+ * Template specializations for some computationally intensive LB
+ * functions of the header file lbHelpers.h, for the D2Q9 grid.
+ */
+
+#ifndef MRT_HELPERS_2D_H
+#define MRT_HELPERS_2D_H
+
+namespace olb {
+
+ 
+
+// Efficient specialization for D2Q9 lattice
+template<typename T>
+struct mrtHelpers<T,descriptors::MRTD2Q9Descriptor> {
+  using DESCRIPTOR = descriptors::MRTD2Q9Descriptor;
+
+  /// Computation of all equilibrium distribution (in momenta space)
+  static void computeEquilibrium( T momentaEq[9],
+                                  T rho, const T u[2],
+                                  const T uSqr )
+  {
+    // momentaEq[0] = rho;
+    momentaEq[1] = rho*(-(T)2 + (T)3*uSqr);
+    momentaEq[2] = rho*((T)1 - (T)3*uSqr);
+    // momentaEq[3] = rho*u[0];
+    momentaEq[4] = rho*-u[0];
+    // momentaEq[5] = rho*u[1];
+    momentaEq[6] = rho*-u[1];
+    momentaEq[7] = rho*(u[0]*u[0] - u[1]*u[1]);
+    momentaEq[8] = rho*u[0]*u[1];
+  }
+
+  /// Computation of all momenta (specialized for d2q9)
+  static void computeMomenta(T momenta[9], Cell<T,DESCRIPTOR> &cell)
+  {
+    //         momenta[0] = cell[0] + cell[1] + cell[2] + cell[3] +
+    //                 cell[4] + cell[5] + cell[6] + cell[7] + cell[8] + (T)1;
+
+    momenta[1] = -(T)4*cell[0] +(T)2*cell[1] - cell[2] + (T)2*cell[3] - cell[4] +
+                 (T)2*cell[5] - cell[6] + (T)2*cell[7] - cell[8] - (T)2;
+
+    momenta[2] = (T)4*cell[0] + cell[1] - (T)2*cell[2] + cell[3] - (T)2*cell[4] +
+                 cell[5] - (T)2*cell[6] + cell[7] - (T)2*cell[8] + (T)1;
+
+    //         momenta[3] = - cell[1] - cell[2] - cell[3] +
+    //                 cell[5] + cell[6] + cell[7];
+
+    momenta[4] = - cell[1] + (T)2*cell[2] - cell[3] +
+                 cell[5] - (T)2*cell[6] + cell[7];
+
+    //         momenta[5] = cell[1] - cell[3] - cell[4] -
+    //                 cell[5] + cell[7] + cell[8];
+
+    momenta[6] = cell[1] - cell[3] + (T)2*cell[4] -
+                 cell[5] + cell[7] - (T)2*cell[8];
+
+    momenta[7] = cell[2] - cell[4] + cell[6] - cell[8];
+
+    momenta[8] = - cell[1] + cell[3] - cell[5] + cell[7];
+  }
+
+  /// MRT collision step
+  static T mrtCollision( Cell<T,DESCRIPTOR>& cell,
+                         T rho, const T u[2],
+                         T invM_S[9][9] )
+  {
+    T uSqr = util::normSqr<T,2>(u);
+    T momenta[9];
+    T momentaEq[9];
+
+    computeMomenta(momenta,cell);
+    computeEquilibrium(momentaEq,rho,u,uSqr);
+
+    T mom1 = momenta[1] - momentaEq[1];
+    T mom2 = momenta[2] - momentaEq[2];
+    T mom4 = momenta[4] - momentaEq[4];
+    T mom6 = momenta[6] - momentaEq[6];
+    T mom7 = momenta[7] - momentaEq[7];
+    T mom8 = momenta[8] - momentaEq[8];
+
+    cell[0] -= invM_S[0][1]*mom1 +
+               invM_S[0][2]*mom2;
+
+    cell[1] -= invM_S[1][1]*mom1 +
+               invM_S[1][2]*mom2 +
+               invM_S[1][4]*mom4 +
+               invM_S[1][6]*mom6 +
+               invM_S[1][8]*mom8;
+
+    cell[2] -= invM_S[2][1]*mom1 +
+               invM_S[2][2]*mom2 +
+               invM_S[2][4]*mom4 +
+               invM_S[2][7]*mom7;
+
+    cell[3] -= invM_S[3][1]*mom1 +
+               invM_S[3][2]*mom2 +
+               invM_S[3][4]*mom4 +
+               invM_S[3][6]*mom6 +
+               invM_S[3][8]*mom8;
+
+    cell[4] -= invM_S[4][1]*mom1 +
+               invM_S[4][2]*mom2 +
+               invM_S[4][6]*mom6 +
+               invM_S[4][7]*mom7;
+
+    cell[5] -= invM_S[5][1]*mom1 +
+               invM_S[5][2]*mom2 +
+               invM_S[5][4]*mom4 +
+               invM_S[5][6]*mom6 +
+               invM_S[5][8]*mom8;
+
+    cell[6] -= invM_S[6][1]*mom1 +
+               invM_S[6][2]*mom2 +
+               invM_S[6][4]*mom4 +
+               invM_S[6][7]*mom7;
+
+    cell[7] -= invM_S[7][1]*mom1 +
+               invM_S[7][2]*mom2 +
+               invM_S[7][4]*mom4 +
+               invM_S[7][6]*mom6 +
+               invM_S[7][8]*mom8;
+
+    cell[8] -= invM_S[8][1]*mom1 +
+               invM_S[8][2]*mom2 +
+               invM_S[8][6]*mom6 +
+               invM_S[8][7]*mom7;
+
+    return uSqr;
+  }
+
+  /// MRT collision step
+  static T mrtSGSCollision( Cell<T,DESCRIPTOR>& cell,
+                            T rho, const T u[2], T omega,
+                            T invM_S_SGS[9][9] )
+  {
+    T uSqr = util::normSqr<T,2>(u);
+    T momenta[9];
+    T momentaEq[9];
+
+    computeMomenta(momenta,cell);
+    computeEquilibrium(momentaEq,rho,u,uSqr);
+
+    T mom1 = momenta[1] - momentaEq[1];
+    T mom2 = momenta[2] - momentaEq[2];
+    T mom4 = momenta[4] - momentaEq[4];
+    T mom6 = momenta[6] - momentaEq[6];
+    T mom7 = momenta[7] - momentaEq[7];
+    T mom8 = momenta[8] - momentaEq[8];
+
+    cell[0] -= invM_S_SGS[0][1]*mom1 +
+               invM_S_SGS[0][2]*mom2;
+
+    cell[1] -= invM_S_SGS[1][1]*mom1/ +
+               invM_S_SGS[1][2]*mom2 +
+               invM_S_SGS[1][4]*mom4 +
+               invM_S_SGS[1][6]*mom6 +
+               invM_S_SGS[1][8]*mom8;
+
+    cell[2] -= invM_S_SGS[2][1]*mom1 +
+               invM_S_SGS[2][2]*mom2 +
+               invM_S_SGS[2][4]*mom4 +
+               invM_S_SGS[2][7]*mom7;
+
+    cell[3] -= invM_S_SGS[3][1]*mom1 +
+               invM_S_SGS[3][2]*mom2 +
+               invM_S_SGS[3][4]*mom4 +
+               invM_S_SGS[3][6]*mom6 +
+               invM_S_SGS[3][8]*mom8;
+
+    cell[4] -= invM_S_SGS[4][1]*mom1 +
+               invM_S_SGS[4][2]*mom2 +
+               invM_S_SGS[4][6]*mom6 +
+               invM_S_SGS[4][7]*mom7;
+
+    cell[5] -= invM_S_SGS[5][1]*mom1 +
+               invM_S_SGS[5][2]*mom2 +
+               invM_S_SGS[5][4]*mom4 +
+               invM_S_SGS[5][6]*mom6 +
+               invM_S_SGS[5][8]*mom8;
+
+    cell[6] -= invM_S_SGS[6][1]*mom1 +
+               invM_S_SGS[6][2]*mom2 +
+               invM_S_SGS[6][4]*mom4 +
+               invM_S_SGS[6][7]*mom7;
+
+    cell[7] -= invM_S_SGS[7][1]*mom1 +
+               invM_S_SGS[7][2]*mom2 +
+               invM_S_SGS[7][4]*mom4 +
+               invM_S_SGS[7][6]*mom6 +
+               invM_S_SGS[7][8]*mom8;
+
+    cell[8] -= invM_S_SGS[8][1]*mom1 +
+               invM_S_SGS[8][2]*mom2 +
+               invM_S_SGS[8][6]*mom6 +
+               invM_S_SGS[8][7]*mom7;
+
+    return uSqr;
+  }
+
+};
+
+
+}  // namespace olb
+
+#endif