Install Type Tag for TPFA Flow Problems

Makes this accessible for out-of-tree uses.

CMakeLists_files.cmake

@@ -855,6 +855,7 @@ list (APPEND PUBLIC_HEADER_FILES
   opm/simulators/flow/SimulatorSerializer.hpp
   opm/simulators/flow/SolutionContainers.hpp
   opm/simulators/flow/SubDomain.hpp
+  opm/simulators/flow/TTagFlowProblemTPFA.hpp
   opm/simulators/flow/TracerModel.hpp
   opm/simulators/flow/Transmissibility.hpp
   opm/simulators/flow/Transmissibility_impl.hpp

flow/flow_blackoil.hpp

@@ -17,15 +17,9 @@
 #ifndef FLOW_BLACKOIL_TPFA_HPP
 #define FLOW_BLACKOIL_TPFA_HPP
 
-#include <memory>
+#include <opm/simulators/flow/TTagFlowProblemTPFA.hpp>
-#include <tuple>
 
-namespace Opm::Properties::TTag {
+#include <memory>
-    struct FlowProblem;
-    struct FlowProblemTPFA {
-        using InheritsFrom = std::tuple<FlowProblem>;
-    };
-}
 
 namespace Opm {
 

opm/simulators/flow/TTagFlowProblemTPFA.hpp

@@ -0,0 +1,40 @@
+/*
+  Copyright 2025 Equinor ASA.
+
+  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 TTAG_FLOW_PROBLEM_TPFA_HPP
+#define TTAG_FLOW_PROBLEM_TPFA_HPP
+
+#include <tuple>
+
+namespace Opm::Properties::TTag {
+
+    struct FlowProblem;
+
+    /// Specialised type tag for simulations that can use the customised
+    /// assembly process for TPFA discretisation schemes.
+    ///
+    /// All properties are otherwise the same as for the regular
+    /// FlowProblem.
+    struct FlowProblemTPFA {
+        using InheritsFrom = std::tuple<FlowProblem>;
+    };
+
+} // namespace Opm::Properties::TTag
+
+#endif // TTAG_FLOW_PROBLEM_TPFA_HPP