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diff --git a/src/dynamics/firstOrderLbHelpers2D.h b/src/dynamics/firstOrderLbHelpers2D.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
+ * Efficient 2D specializations for lbHelpersD2Q9.h
+ */
+#ifndef FIRST_ORDER_LB_HELPERS_2D_H
+#define FIRST_ORDER_LB_HELPERS_2D_H
+
+namespace olb {
+
+/// Compute Pi tensor efficiently on D2Q9 lattice
+namespace neqPiD2Q9 {
+
+using namespace olb::util::tensorIndices2D;
+
+template<typename T>
+T fromPiToFneq0(const T pi[3])
+{
+  return (T)2 * (-(T)1/(T)3*pi[xx] - (T)1/(T)3*pi[yy]);
+}
+
+template<typename T>
+T fromPiToFneq1(const T pi[3])
+{
+  return (T)1/(T)4 * ((T)1/(T)3*pi[xx] + (T)1/(T)3*pi[yy] - pi[xy]);
+}
+
+template<typename T>
+T fromPiToFneq2(const T pi[3])
+{
+  return (T)1/(T)2 * ((T)2/(T)3*pi[xx] - (T)1/(T)3*pi[yy]);
+}
+
+template<typename T>
+T fromPiToFneq3(const T pi[3])
+{
+  return (T)1/(T)4 * ((T)1/(T)3*pi[xx] + (T)1/(T)3*pi[yy] + pi[xy]);
+}
+
+template<typename T>
+T fromPiToFneq4(const T pi[3])
+{
+  return (T)1/(T)2 * (-(T)1/(T)3*pi[xx] + (T)2/(T)3*pi[yy]);
+}
+
+}  // namespace neqPiD2Q9
+
+template<typename T>
+struct rlbHelpers<T, descriptors::D2Q9<>> {
+
+  static T rlbCollision (
+    Cell<T,descriptors::D2Q9<>>& cell,
+    T rho, const T u[2], const T pi[3], T omega )
+  {
+    typedef lbHelpers<T, descriptors::D2Q9<>> LH;
+    const T uSqr = u[0]*u[0] + u[1]*u[1];
+
+    cell[0]  = LH::equilibrium(0, rho, u, uSqr) +
+               ((T)1-omega) * neqPiD2Q9::fromPiToFneq0(pi);
+    cell[1]  = LH::equilibrium(1, rho, u, uSqr) +
+               ((T)1-omega) * neqPiD2Q9::fromPiToFneq1(pi);
+    cell[2]  = LH::equilibrium(2, rho, u, uSqr) +
+               ((T)1-omega) * neqPiD2Q9::fromPiToFneq2(pi);
+    cell[3]  = LH::equilibrium(3, rho, u, uSqr) +
+               ((T)1-omega) * neqPiD2Q9::fromPiToFneq3(pi);
+    cell[4]  = LH::equilibrium(4, rho, u, uSqr) +
+               ((T)1-omega) * neqPiD2Q9::fromPiToFneq4(pi);
+    cell[5]  = LH::equilibrium(5, rho, u, uSqr) +
+               ((T)1-omega) * neqPiD2Q9::fromPiToFneq1(pi);
+    cell[6]  = LH::equilibrium(6, rho, u, uSqr) +
+               ((T)1-omega) * neqPiD2Q9::fromPiToFneq2(pi);
+    cell[7]  = LH::equilibrium(7, rho, u, uSqr) +
+               ((T)1-omega) * neqPiD2Q9::fromPiToFneq3(pi);
+    cell[8]  = LH::equilibrium(8, rho, u, uSqr) +
+               ((T)1-omega) * neqPiD2Q9::fromPiToFneq4(pi);
+    return uSqr;
+  }
+
+};  // struct rlbHelpers<D2Q9<>>
+
+}  // namespace olb
+
+
+#endif