Add connectionMultiPhaseUpwind() free function.

opm/autodiff/multiPhaseUpwind.hpp

@@ -0,0 +1,45 @@
+/*
+  Copyright 2015, 2016 SINTEF ICT, Applied Mathematics.
+  Copyright 2016 Statoil AS.
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM 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 3 of the License, or
+  (at your option) any later version.
+
+  OPM 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 OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef OPM_MULTIPHASEUPWIND_HEADER_INCLUDED
+#define OPM_MULTIPHASEUPWIND_HEADER_INCLUDED
+
+#include <array>
+
+namespace Opm
+{
+    /// Compute upwind directions for three-phase flow across a connection.
+    ///
+    /// @param[in]  head_diff           head differences by phase
+    /// @param[in]  mob1                phase mobilities for first cell
+    /// @param[in]  mob2                phase mobilities for second cell
+    /// @param[in]  transmissibility    tranmissibility of connection
+    /// @param[in]  flux                total volume flux across connection
+    /// @return array containing, for each phase, 1.0 if flow in the
+    ///         direction of the connection, -1.0 if flow in the opposite
+    ///         direction.
+    std::array<double, 3> connectionMultiPhaseUpwind(const std::array<double, 3>& head_diff,
+                                                     const std::array<double, 3>& mob1,
+                                                     const std::array<double, 3>& mob2,
+                                                     const double transmissibility,
+                                                     const double flux);
+} // namespace Opm
+
+#endif // OPM_MULTIPHASEUPWIND_HEADER_INCLUDED