Move refinement to contrib

14 files changed, 1284 insertions, 0 deletions

diff --git a/src/contrib/MakeHeader b/src/contrib/MakeHeader
new file mode 100644
index 0000000..67c5005
--- /dev/null
+++ b/src/contrib/MakeHeader
@@ -0,0 +1,21 @@
+#  This file is part of the OpenLB library
+#
+#  Copyright (C) 2007 Mathias Krause
+#  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.
diff --git a/src/contrib/contrib2D.h b/src/contrib/contrib2D.h
new file mode 100644
index 0000000..eeb5b79
--- /dev/null
+++ b/src/contrib/contrib2D.h
@@ -0,0 +1,38 @@
+/*  This file is part of the OpenLB library
+ *
+ *  Copyright (C) 2007 the OpenLB project
+ *
+ *  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
+ * Groups all the 2D include files in the contrib directory.
+ */
+
+#include "advectionDiffusionVelocityCouplingPostProcessor2D.h"
+#include "HerschelBulkleyBGKdynamics.h"
+//#include "movingBoundaryBGKdynamics.h"
+//#include "movingBoundaryFunctors.h"
+#include "keepIncomingBoundary2D.h"
+#include "keepIncomingDynamics.h"
+//#include "straightBouzidiBoundary2D.h"
+//#include "straightBouzidiDynamics.h"
+#include "entropicLatticeDescriptors.h"
+#include "optEntropicDynamics.h"
+#include "shanLatticeDescriptors.h"
+#include "SmagorinskyHerschelBulkleyPorousBGKdynamics.h"
+//#include "graphLoadBalancer.h"
+#include "refinement/refinement2D.h"
diff --git a/src/contrib/contrib2D.hh b/src/contrib/contrib2D.hh
new file mode 100644
index 0000000..00f6c20
--- /dev/null
+++ b/src/contrib/contrib2D.hh
@@ -0,0 +1,25 @@
+/*  This file is part of the OpenLB library
+ *
+ *  Copyright (C) 2007 the OpenLB project
+ *
+ *  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
+ * Groups all the generic 2D template files in the contrib directory.
+ */
+
+#include "refinement/refinement2D.hh"
diff --git a/src/contrib/module.mk b/src/contrib/module.mk
new file mode 100644
index 0000000..6e42e3e
--- /dev/null
+++ b/src/contrib/module.mk
@@ -0,0 +1,27 @@
+#  This file is part of the OpenLB library
+#
+#  Copyright (C) 2017 Markus Mohrhard
+#  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.
+
+current_dir := $(dir $(word $(words $(MAKEFILE_LIST)),$(MAKEFILE_LIST)))
+
+include $(addsuffix /MakeHeader, $(current_dir))
+
+LIB_OBJECTS += $(foreach file, $($(BUILDTYPE)), $(OBJDIR)/$(current_dir)$(file).o)
diff --git a/src/contrib/refinement/MakeHeader b/src/contrib/refinement/MakeHeader
new file mode 100644
index 0000000..bfcbf33
--- /dev/null
+++ b/src/contrib/refinement/MakeHeader
@@ -0,0 +1,27 @@
+#  This file is part of the OpenLB library
+#
+#  Copyright (C) 2019 Adrian Kummerländer
+#  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.
+
+
+generic        :=
+
+precompiled    := grid2D \
+                  coupler2D
diff --git a/src/contrib/refinement/coupler2D.cpp b/src/contrib/refinement/coupler2D.cpp
new file mode 100644
index 0000000..733d7c9
--- /dev/null
+++ b/src/contrib/refinement/coupler2D.cpp
@@ -0,0 +1,35 @@
+/*  This file is part of the OpenLB library
+ *
+ *  Copyright (C) 2019 Adrian Kummerländer
+ *  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.
+ */
+
+#include "coupler2D.h"
+#include "coupler2D.hh"
+
+#include "dynamics/latticeDescriptors.h"
+
+namespace olb {
+
+template class Coupler2D<double,descriptors::D2Q9<>>;
+template class FineCoupler2D<double,descriptors::D2Q9<>>;
+template class CoarseCoupler2D<double,descriptors::D2Q9<>>;
+
+}
diff --git a/src/contrib/refinement/coupler2D.h b/src/contrib/refinement/coupler2D.h
new file mode 100644
index 0000000..9b310b7
--- /dev/null
+++ b/src/contrib/refinement/coupler2D.h
@@ -0,0 +1,90 @@
+/*  This file is part of the OpenLB library
+ *
+ *  Copyright (C) 2019 Adrian Kummerländer
+ *  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.
+*/
+
+#ifndef REFINEMENT_COUPLER_2D_H
+#define REFINEMENT_COUPLER_2D_H
+
+#include "grid2D.h"
+
+namespace olb {
+
+
+template <typename T, typename DESCRIPTOR>
+class Coupler2D {
+protected:
+  Grid2D<T,DESCRIPTOR>& _coarse;
+  Grid2D<T,DESCRIPTOR>& _fine;
+
+  const int  _coarseSize;
+  const int  _fineSize;
+  const bool _vertical;
+
+  const Vector<T,2> _physOrigin;
+
+  const Vector<int,3>& getFineLatticeR(int y) const;
+  const Vector<int,3>& getCoarseLatticeR(int y) const;
+
+  T getScalingFactor() const;
+  T getInvScalingFactor() const;
+
+private:
+  std::vector<Vector<int,3>> _coarseLatticeR;
+  std::vector<Vector<int,3>> _fineLatticeR;
+
+public:
+  Coupler2D(Grid2D<T,DESCRIPTOR>& coarse, Grid2D<T,DESCRIPTOR>& fine,
+            Vector<T,2> origin, Vector<T,2> extend);
+
+};
+
+template <typename T, typename DESCRIPTOR>
+class FineCoupler2D : public Coupler2D<T,DESCRIPTOR> {
+private:
+  std::vector<Vector<T,1>>             _c2f_rho;
+  std::vector<Vector<T,DESCRIPTOR::d>> _c2f_u;
+  std::vector<Vector<T,DESCRIPTOR::q>> _c2f_fneq;
+
+public:
+  FineCoupler2D(Grid2D<T,DESCRIPTOR>& coarse, Grid2D<T,DESCRIPTOR>& fine,
+                Vector<T,2> origin, Vector<T,2> extend);
+
+  void store();
+  void interpolate();
+  void couple();
+
+};
+
+template <typename T, typename DESCRIPTOR>
+class CoarseCoupler2D : public Coupler2D<T,DESCRIPTOR> {
+public:
+  CoarseCoupler2D(Grid2D<T,DESCRIPTOR>& coarse, Grid2D<T,DESCRIPTOR>& fine,
+                  Vector<T,2> origin, Vector<T,2> extend);
+
+  void couple();
+
+};
+
+
+}
+
+#endif
diff --git a/src/contrib/refinement/coupler2D.hh b/src/contrib/refinement/coupler2D.hh
new file mode 100644
index 0000000..4c8b424
--- /dev/null
+++ b/src/contrib/refinement/coupler2D.hh
@@ -0,0 +1,349 @@
+/*  This file is part of the OpenLB library
+ *
+ *  Copyright (C) 2019 Adrian Kummerländer
+ *  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.
+*/
+
+#ifndef REFINEMENT_COUPLER_2D_HH
+#define REFINEMENT_COUPLER_2D_HH
+
+#include "coupler2D.h"
+
+#include "dynamics/lbHelpers.h"
+
+namespace olb {
+
+template <typename T, typename DESCRIPTOR>
+T Coupler2D<T,DESCRIPTOR>::getScalingFactor() const
+{
+  const T coarseTau = _coarse.getConverter().getLatticeRelaxationTime();
+  return (coarseTau - 0.25) / coarseTau;
+}
+
+template <typename T, typename DESCRIPTOR>
+T Coupler2D<T,DESCRIPTOR>::getInvScalingFactor() const
+{
+  return 1./getScalingFactor();
+}
+
+template <typename T, typename DESCRIPTOR>
+const Vector<int,3>& Coupler2D<T,DESCRIPTOR>::getFineLatticeR(int y) const
+{
+  return _fineLatticeR[y];
+}
+
+template <typename T, typename DESCRIPTOR>
+const Vector<int,3>& Coupler2D<T,DESCRIPTOR>::getCoarseLatticeR(int y) const
+{
+  return _coarseLatticeR[y];
+}
+
+template <typename T, typename DESCRIPTOR>
+Coupler2D<T,DESCRIPTOR>::Coupler2D(Grid2D<T,DESCRIPTOR>& coarse, Grid2D<T,DESCRIPTOR>& fine,
+                                   Vector<T,2> origin, Vector<T,2> extend):
+  _coarse(coarse),
+  _fine(fine),
+  _coarseSize(floor(extend.norm() / coarse.getConverter().getPhysDeltaX() + 0.5)+1),
+  _fineSize(2*_coarseSize-1),
+  _vertical(util::nearZero(extend[0])),
+  _physOrigin(_coarse.alignOriginToGrid(origin)),
+  _coarseLatticeR(_coarseSize),
+  _fineLatticeR(_fineSize)
+{
+  OLB_ASSERT(util::nearZero(extend[0]) || util::nearZero(extend[1]), "Coupling is only implemented alongside unit vectors");
+
+  const auto& coarseGeometry = _coarse.getCuboidGeometry();
+  const auto& fineGeometry   = _fine.getCuboidGeometry();
+
+  const T deltaX = _fine.getConverter().getPhysDeltaX();
+  const Vector<T,2> stepPhysR = _vertical ? Vector<T,2> {0, deltaX} :
+                                Vector<T,2> {deltaX, 0};
+
+  for (int i=0; i < _fineSize; ++i) {
+    if (i % 2 == 0) {
+      coarseGeometry.getLatticeR(_physOrigin + i*stepPhysR, _coarseLatticeR[i/2]);
+    }
+
+    fineGeometry.getLatticeR(_physOrigin + i*stepPhysR, _fineLatticeR[i]);
+  }
+}
+
+
+template <typename T, typename DESCRIPTOR>
+FineCoupler2D<T,DESCRIPTOR>::FineCoupler2D(Grid2D<T,DESCRIPTOR>& coarse, Grid2D<T,DESCRIPTOR>& fine,
+    Vector<T,2> origin, Vector<T,2> extend):
+  Coupler2D<T,DESCRIPTOR>(coarse, fine, origin, extend),
+  _c2f_rho(this->_coarseSize),
+  _c2f_u(this->_coarseSize, Vector<T,2>(T{})),
+  _c2f_fneq(this->_coarseSize, Vector<T,DESCRIPTOR::q>(T{}))
+{
+  OstreamManager clout(std::cout,"C2F");
+
+  const auto& coarseOrigin = this->getCoarseLatticeR(0);
+  const auto& fineOrigin   = this->getFineLatticeR(0);
+
+  clout << "coarse origin: " << coarseOrigin[0] << " " << coarseOrigin[1] << " " << coarseOrigin[2] << std::endl;
+  clout << "fine origin:   " << fineOrigin[0]   << " " << fineOrigin[1]   << " " << fineOrigin[2]   << std::endl;
+  clout << "fine size:     " << this->_fineSize << std::endl;
+}
+
+template <typename T, typename DESCRIPTOR>
+void FineCoupler2D<T,DESCRIPTOR>::store()
+{
+  auto& coarseLattice = this->_coarse.getSuperLattice();
+
+#ifdef PARALLEL_MODE_OMP
+  #pragma omp parallel for
+#endif
+  for (int y=0; y < this->_coarseSize; ++y) {
+    const auto pos = this->getCoarseLatticeR(y);
+    T rho{};
+    T u[2] {};
+    T fNeq[DESCRIPTOR::q] {};
+    Cell<T,DESCRIPTOR> coarseCell;
+    coarseLattice.get(pos, coarseCell);
+    lbHelpers<T,DESCRIPTOR>::computeRhoU(coarseCell, rho, u);
+    lbHelpers<T,DESCRIPTOR>::computeFneq(coarseCell, fNeq, rho, u);
+
+    _c2f_rho[y]  = Vector<T,1>(rho);
+    _c2f_u[y]    = Vector<T,2>(u);
+    _c2f_fneq[y] = Vector<T,DESCRIPTOR::q>(fNeq);
+  }
+}
+
+template <typename T, unsigned N>
+Vector<T,N> order2interpolation(const Vector<T,N>& f0, const Vector<T,N>& f1)
+{
+  return 0.5 * (f0 + f1);
+}
+
+template <typename T, unsigned N>
+Vector<T,N> order2interpolation(const std::vector<Vector<T,N>>& data, int y)
+{
+  return 0.5 * (data[y] + data[y+1]);
+}
+
+template <typename T, unsigned N>
+Vector<T,N> order3interpolation(const std::vector<Vector<T,N>>& data, int y, bool ascending)
+{
+  if (ascending) {
+    return 3./8. * data[y] + 3./4. * data[y+1] - 1./8. * data[y+2];
+  }
+  else {
+    return 3./8. * data[y] + 3./4. * data[y-1] - 1./8. * data[y-2];
+  }
+}
+
+template <typename T, unsigned N>
+Vector<T,N> order4interpolation(const std::vector<Vector<T,N>>& data, int y)
+{
+  return 9./16. * (data[y] + data[y+1]) - 1./16. * (data[y-1] + data[y+2]);
+}
+
+
+template <typename T, typename DESCRIPTOR>
+void FineCoupler2D<T,DESCRIPTOR>::interpolate()
+{
+  auto& coarseLattice = this->_coarse.getSuperLattice();
+
+#ifdef PARALLEL_MODE_OMP
+  #pragma omp parallel for
+#endif
+  for (int y=0; y < this->_coarseSize; ++y) {
+    Cell<T,DESCRIPTOR> coarseCell;
+    coarseLattice.get(this->getCoarseLatticeR(y), coarseCell);
+
+    T rho{};
+    T u[2] {};
+    lbHelpers<T,DESCRIPTOR>::computeRhoU(coarseCell, rho, u);
+
+    _c2f_rho[y] = order2interpolation(Vector<T,1>(rho), _c2f_rho[y]);
+    _c2f_u[y]   = order2interpolation(Vector<T,2>(u), _c2f_u[y]);
+
+    T fNeq[DESCRIPTOR::q] {};
+    lbHelpers<T,DESCRIPTOR>::computeFneq(coarseCell, fNeq, rho, u);
+
+    _c2f_fneq[y] = order2interpolation(Vector<T,DESCRIPTOR::q>(fNeq), _c2f_fneq[y]);
+  }
+}
+
+template <typename T, typename DESCRIPTOR>
+void FineCoupler2D<T,DESCRIPTOR>::couple()
+{
+  const auto& coarseLattice = this->_coarse.getSuperLattice();
+  auto& fineLattice   = this->_fine.getSuperLattice();
+
+#ifdef PARALLEL_MODE_OMP
+  #pragma omp parallel for
+#endif
+  for (int y=0; y < this->_coarseSize; ++y) {
+    const auto& coarsePos = this->getCoarseLatticeR(y);
+    const auto& finePos   = this->getFineLatticeR(2*y);
+
+    T fEq[DESCRIPTOR::q] {};
+    Cell<T,DESCRIPTOR> coarseCell;
+    coarseLattice.get(coarsePos, coarseCell);
+    lbHelpers<T,DESCRIPTOR>::computeFeq(coarseCell, fEq);
+
+    Cell<T,DESCRIPTOR> cell;
+    fineLattice.get(finePos, cell);
+    for (int iPop=0; iPop < DESCRIPTOR::q; ++iPop) {
+      cell[iPop] = fEq[iPop] + this->getScalingFactor() * _c2f_fneq[y][iPop];
+    }
+    fineLattice.set(finePos, cell);
+  }
+
+#ifdef PARALLEL_MODE_OMP
+  #pragma omp parallel for
+#endif
+  for (int y=1; y < this->_coarseSize-2; ++y) {
+    const auto rho  = order4interpolation(_c2f_rho,  y);
+    const auto u    = order4interpolation(_c2f_u,    y);
+    const auto fneq = order4interpolation(_c2f_fneq, y);
+
+    const T uSqr = u*u;
+
+    const auto finePos = this->getFineLatticeR(1+2*y);
+    Cell<T,DESCRIPTOR> fineCell;
+    fineLattice.get(finePos, fineCell);
+
+    for (int iPop=0; iPop < DESCRIPTOR::q; ++iPop) {
+      fineCell[iPop] = lbHelpers<T,DESCRIPTOR>::equilibrium(iPop, rho[0], u.data, uSqr)
+                       + this->getScalingFactor() * fneq[iPop];
+    }
+
+    fineLattice.set(finePos, fineCell);
+  }
+
+  {
+    const auto rho  = order3interpolation(_c2f_rho,  0, true);
+    const auto u    = order3interpolation(_c2f_u,    0, true);
+    const auto fneq = order3interpolation(_c2f_fneq, 0, true);
+
+    const T uSqr = u*u;
+
+    const auto& finePos = this->getFineLatticeR(1);
+    Cell<T,DESCRIPTOR> fineCell;
+    fineLattice.get(finePos, fineCell);
+
+    for (int iPop=0; iPop < DESCRIPTOR::q; ++iPop) {
+      fineCell[iPop] = lbHelpers<T,DESCRIPTOR>::equilibrium(iPop, rho[0], u.data, uSqr)
+                       + this->getScalingFactor() * fneq[iPop];
+    }
+
+    fineLattice.set(finePos, fineCell);
+  }
+
+  {
+    const auto rho  = order3interpolation(_c2f_rho,  this->_coarseSize-1, false);
+    const auto u    = order3interpolation(_c2f_u,    this->_coarseSize-1, false);
+    const auto fneq = order3interpolation(_c2f_fneq, this->_coarseSize-1, false);
+
+    const T uSqr = u*u;
+
+    const auto& finePos = this->getFineLatticeR(this->_fineSize-2);
+    Cell<T,DESCRIPTOR> fineCell;
+    fineLattice.get(finePos, fineCell);
+
+    for (int iPop=0; iPop < DESCRIPTOR::q; ++iPop) {
+      fineCell[iPop] = lbHelpers<T,DESCRIPTOR>::equilibrium(iPop, rho[0], u.data, uSqr)
+                       + this->getScalingFactor() * fneq[iPop];
+    }
+
+    fineLattice.set(finePos, fineCell);
+  }
+}
+
+
+template <typename T, typename DESCRIPTOR>
+void computeRestrictedFneq(const SuperLattice2D<T,DESCRIPTOR>& lattice,
+                           Vector<int,3> latticeR,
+                           T restrictedFneq[DESCRIPTOR::q])
+{
+  for (int iPop=0; iPop < DESCRIPTOR::q; ++iPop) {
+    const auto neighbor = latticeR + Vector<int,3> {0, descriptors::c<DESCRIPTOR>(iPop,0), descriptors::c<DESCRIPTOR>(iPop,1)};
+    Cell<T,DESCRIPTOR> cell;
+    lattice.get(neighbor, cell);
+
+    T fNeq[DESCRIPTOR::q] {};
+    lbHelpers<T,DESCRIPTOR>::computeFneq(cell, fNeq);
+
+    for (int jPop=0; jPop < DESCRIPTOR::q; ++jPop) {
+      restrictedFneq[jPop] += fNeq[jPop];
+    }
+  }
+
+  for (int iPop=0; iPop < DESCRIPTOR::q; ++iPop) {
+    restrictedFneq[iPop] /= DESCRIPTOR::q;
+  }
+}
+
+template <typename T, typename DESCRIPTOR>
+CoarseCoupler2D<T,DESCRIPTOR>::CoarseCoupler2D(
+  Grid2D<T,DESCRIPTOR>& coarse, Grid2D<T,DESCRIPTOR>& fine,
+  Vector<T,2> origin, Vector<T,2> extend):
+  Coupler2D<T,DESCRIPTOR>(coarse, fine, origin, extend)
+{
+  OstreamManager clout(std::cout,"F2C");
+
+  const auto& coarseOrigin = this->getCoarseLatticeR(0);
+  const auto& fineOrigin   = this->getFineLatticeR(0);
+
+  clout << "coarse origin: " << coarseOrigin[0] << " " << coarseOrigin[1] << " " << coarseOrigin[2] << std::endl;
+  clout << "fine origin:   " << fineOrigin[0]   << " " << fineOrigin[1]   << " " << fineOrigin[2]   << std::endl;
+  clout << "coarse size:   " << this->_coarseSize << std::endl;
+}
+
+template <typename T, typename DESCRIPTOR>
+void CoarseCoupler2D<T,DESCRIPTOR>::couple()
+{
+  const auto& fineLattice = this->_fine.getSuperLattice();
+  auto& coarseLattice = this->_coarse.getSuperLattice();
+
+#ifdef PARALLEL_MODE_OMP
+  #pragma omp parallel for
+#endif
+  for (int y=0; y < this->_coarseSize; ++y) {
+    const auto& finePos   = this->getFineLatticeR(2*y);
+    const auto& coarsePos = this->getCoarseLatticeR(y);
+
+    T fEq[DESCRIPTOR::q] {};
+    Cell<T,DESCRIPTOR> fineCell;
+    fineLattice.get(finePos, fineCell);
+    lbHelpers<T,DESCRIPTOR>::computeFeq(fineCell, fEq);
+
+    T fNeq[DESCRIPTOR::q] {};
+    computeRestrictedFneq(fineLattice, finePos, fNeq);
+
+    Cell<T,DESCRIPTOR> coarseCell;
+    coarseLattice.get(coarsePos, coarseCell);
+
+    for (int iPop=0; iPop < DESCRIPTOR::q; ++iPop) {
+      coarseCell[iPop] = fEq[iPop] + this->getInvScalingFactor() * fNeq[iPop];
+    }
+
+    coarseLattice.set(coarsePos, coarseCell);
+  }
+}
+
+
+}
+
+#endif
diff --git a/src/contrib/refinement/grid2D.cpp b/src/contrib/refinement/grid2D.cpp
new file mode 100644
index 0000000..4472fc7
--- /dev/null
+++ b/src/contrib/refinement/grid2D.cpp
@@ -0,0 +1,34 @@
+/*  This file is part of the OpenLB library
+ *
+ *  Copyright (C) 2019 Adrian Kummerländer
+ *  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.
+ */
+
+#include "grid2D.h"
+#include "grid2D.hh"
+
+#include "dynamics/latticeDescriptors.h"
+
+namespace olb {
+
+template class Grid2D<double,descriptors::D2Q9<>>;
+template class RefiningGrid2D<double,descriptors::D2Q9<>>;
+
+}
diff --git a/src/contrib/refinement/grid2D.h b/src/contrib/refinement/grid2D.h
new file mode 100644
index 0000000..51d19ce
--- /dev/null
+++ b/src/contrib/refinement/grid2D.h
@@ -0,0 +1,169 @@
+/*  This file is part of the OpenLB library
+ *
+ *  Copyright (C) 2019 Adrian Kummerländer
+ *  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.
+*/
+
+#ifndef REFINEMENT_GRID_2D_H
+#define REFINEMENT_GRID_2D_H
+
+#include <memory>
+#include <vector>
+#include <string>
+#include <functional>
+
+#include "core/unitConverter.h"
+#include "core/superLattice2D.h"
+#include "geometry/superGeometry2D.h"
+#include "geometry/cuboidGeometry2D.h"
+#include "geometry/superGeometry2D.h"
+#include "communication/loadBalancer.h"
+#include "functors/analytical/indicator/indicatorF2D.h"
+#include "utilities/functorPtr.h"
+#include "utilities/namedType.h"
+
+namespace olb {
+
+
+template <typename T, typename DESCRIPTOR> class FineCoupler2D;
+template <typename T, typename DESCRIPTOR> class CoarseCoupler2D;
+template <typename T, typename DESCRIPTOR> class RefiningGrid2D;
+
+template <typename T, typename DESCRIPTOR> class sOnLatticeBoundaryCondition2D;
+template <typename T, typename DESCRIPTOR> class sOffLatticeBoundaryCondition2D;
+
+template <typename T>
+using RelaxationTime = utilities::NamedType<T,struct NamedRelaxationTime>;
+
+template <typename T>
+using LatticeVelocity = utilities::NamedType<T,struct NamedLatticeVelocity>;
+
+template <typename T>
+struct Characteristics {
+  Characteristics(T l, T u, T nu, T rho):
+    length(l),
+    velocity(u),
+    viscosity(nu),
+    density(rho) { }
+
+  Characteristics(int Re):
+    Characteristics(1.0, 1.0, 1.0/Re, 1.0) { }
+
+  const T length;
+  const T velocity;
+  const T viscosity;
+  const T density;
+};
+
+
+template <typename T, typename DESCRIPTOR>
+class Grid2D {
+protected:
+  FunctorPtr<IndicatorF2D<T>> _domainF;
+  const Characteristics<T> _characteristics;
+
+  std::unique_ptr<UnitConverter<T,DESCRIPTOR>>  _converter;
+  std::unique_ptr<CuboidGeometry2D<T>>          _cuboids;
+  std::unique_ptr<LoadBalancer<T>>              _balancer;
+  std::unique_ptr<SuperGeometry2D<T>>           _geometry;
+  std::unique_ptr<SuperLattice2D<T,DESCRIPTOR>> _lattice;
+
+  std::vector<std::unique_ptr<Dynamics<T,DESCRIPTOR>>>                       _dynamics;
+  std::vector<std::unique_ptr<sOnLatticeBoundaryCondition2D<T,DESCRIPTOR>>>  _onLatticeBoundaryConditions;
+  std::vector<std::unique_ptr<sOffLatticeBoundaryCondition2D<T,DESCRIPTOR>>> _offLatticeBoundaryConditions;
+
+  std::vector<std::unique_ptr<RefiningGrid2D<T,DESCRIPTOR>>> _fineGrids;
+
+  std::vector<std::unique_ptr<FineCoupler2D<T,DESCRIPTOR>>>   _fineCouplers;
+  std::vector<std::unique_ptr<CoarseCoupler2D<T,DESCRIPTOR>>> _coarseCouplers;
+
+public:
+  Grid2D(FunctorPtr<IndicatorF2D<T>>&& domainF,
+         RelaxationTime<T> tau,
+         int resolution,
+         Characteristics<T> characteristics);
+  Grid2D(FunctorPtr<IndicatorF2D<T>>&& domainF,
+         LatticeVelocity<T> latticeVelocity,
+         int resolution,
+         Characteristics<T> characteristics);
+
+  Grid2D(FunctorPtr<IndicatorF2D<T>>&& domainF, RelaxationTime<T> tau,   int resolution, int re);
+  Grid2D(FunctorPtr<IndicatorF2D<T>>&& domainF, LatticeVelocity<T> uMax, int resolution, int re);
+
+  Characteristics<T> getCharacteristics() const;
+
+  UnitConverter<T,DESCRIPTOR>&  getConverter();
+  CuboidGeometry2D<T>&          getCuboidGeometry();
+  LoadBalancer<T>&              getLoadBalancer();
+  SuperGeometry2D<T>&           getSuperGeometry();
+  SuperLattice2D<T,DESCRIPTOR>& getSuperLattice();
+
+  Dynamics<T,DESCRIPTOR>& addDynamics(std::unique_ptr<Dynamics<T,DESCRIPTOR>>&& dynamics);
+  sOnLatticeBoundaryCondition2D<T,DESCRIPTOR>&  getOnLatticeBoundaryCondition();
+  sOffLatticeBoundaryCondition2D<T,DESCRIPTOR>& getOffLatticeBoundaryCondition();
+
+  void collideAndStream();
+
+  FineCoupler2D<T,DESCRIPTOR>& addFineCoupling(
+    Grid2D<T,DESCRIPTOR>& fineGrid, Vector<T,2> origin, Vector<T,2> extend);
+  CoarseCoupler2D<T,DESCRIPTOR>& addCoarseCoupling(
+    Grid2D<T,DESCRIPTOR>& fineGrid, Vector<T,2> origin, Vector<T,2> extend);
+
+  Vector<T,2> alignOriginToGrid(Vector<T,2> physR) const;
+  Vector<T,2> alignExtendToGrid(Vector<T,2> physR) const;
+
+  RefiningGrid2D<T,DESCRIPTOR>& refine(Vector<T,2> origin, Vector<T,2> extend, bool addCouplers=true);
+
+  void forEachGrid(std::function<void(Grid2D<T,DESCRIPTOR>&)>&& f);
+  void forEachGrid(const std::string& id, std::function<void(Grid2D<T,DESCRIPTOR>&,const std::string&)>&& f);
+
+  /// Returns the finest grid representing a physical position
+  /**
+   * Only works if pos is actually contained in a node of the refinement tree.
+   **/
+  Grid2D<T,DESCRIPTOR>& locate(Vector<T,2> pos);
+
+  std::size_t getActiveVoxelN() const;
+
+};
+
+template <typename T, typename DESCRIPTOR>
+class RefiningGrid2D : public Grid2D<T,DESCRIPTOR> {
+private:
+  const Vector<T,2> _origin;
+  const Vector<T,2> _extend;
+
+  Grid2D<T,DESCRIPTOR>& _parentGrid;
+
+public:
+  RefiningGrid2D(Grid2D<T,DESCRIPTOR>& parentGrid, Vector<T,2> origin, Vector<T,2> extend);
+
+  Vector<T,2> getOrigin() const;
+  Vector<T,2> getExtend() const;
+
+  /// Indicates the subdomain of the coarse grid rendered moot by refinement
+  std::unique_ptr<IndicatorF2D<T>> getRefinedOverlap() const;
+
+};
+
+
+}
+
+#endif
diff --git a/src/contrib/refinement/grid2D.hh b/src/contrib/refinement/grid2D.hh
new file mode 100644
index 0000000..d4310e5
--- /dev/null
+++ b/