From 823f157aee7e275cd46ee5e7ab035335cd0ced95 Mon Sep 17 00:00:00 2001
From: Kai Bao <kai.bao@sintef.no>
Date: Thu, 25 Sep 2025 19:10:19 +0200
Subject: [PATCH] only applying regional multiplier to PINCH NNC

when applyNncMultregT is true. it is consistent with other code design.
---
 opm/simulators/flow/Transmissibility.hpp      |  3 ++-
 opm/simulators/flow/Transmissibility_impl.hpp | 12 ++++++++----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/opm/simulators/flow/Transmissibility.hpp b/opm/simulators/flow/Transmissibility.hpp
index 6d32a44953..6b0ffd34a8 100644
--- a/opm/simulators/flow/Transmissibility.hpp
+++ b/opm/simulators/flow/Transmissibility.hpp
@@ -230,7 +230,8 @@ protected:
     ///
     /// \param cartesianToCompressed Vector containing the compressed index (or -1 for inactive
     ///                              cells) as the element at the cartesian index.
-    void applyPinchNncToGridTrans_(const std::unordered_map<std::size_t,int>& cartesianToCompressed);
+    void applyPinchNncToGridTrans_(const std::unordered_map<std::size_t,int>& cartesianToCompressed,
+                                   bool applyNncMultregT);
 
     /// \brief Multiplies the grid transmissibilities according to EDITNNC.
     void applyEditNncToGridTrans_(const std::unordered_map<std::size_t,int>& globalToLocal);
diff --git a/opm/simulators/flow/Transmissibility_impl.hpp b/opm/simulators/flow/Transmissibility_impl.hpp
index a2c1d0881d..2ebffbc46d 100644
--- a/opm/simulators/flow/Transmissibility_impl.hpp
+++ b/opm/simulators/flow/Transmissibility_impl.hpp
@@ -563,7 +563,7 @@ update(bool global, const TransUpdateQuantities update_quantities,
         // be seen in a parallel. Unfortunately, when we do not use transmissibilities
         // we will only see warnings for the partition of process 0 and also false positives.
         this->applyEditNncToGridTrans_(globalToLocal);
-        this->applyPinchNncToGridTrans_(globalToLocal);
+        this->applyPinchNncToGridTrans_(globalToLocal, applyNncMultregT);
         this->applyNncToGridTrans_(globalToLocal);
         this->applyEditNncrToGridTrans_(globalToLocal);
         if (applyNncMultregT) {
@@ -1054,7 +1054,8 @@ computeFaceProperties(const Intersection& intersection,
 template<class Grid, class GridView, class ElementMapper, class CartesianIndexMapper, class Scalar>
 void
 Transmissibility<Grid,GridView,ElementMapper,CartesianIndexMapper,Scalar>::
-applyPinchNncToGridTrans_(const std::unordered_map<std::size_t,int>& cartesianToCompressed)
+applyPinchNncToGridTrans_(const std::unordered_map<std::size_t,int>& cartesianToCompressed,
+                          const bool applyNncMultregT)
 {
     const auto& pinchNnc = eclState_.getPinchNNC();
     const auto& transMult = this->eclState_.getTransMult();
@@ -1089,8 +1090,11 @@ applyPinchNncToGridTrans_(const std::unordered_map<std::size_t,int>& cartesianTo
                 // the correctly calculated transmissibility is stored in
                 // the NNC. Overwrite previous value with it.
                 // taking the region multiplier into account.
-                const auto mult = transMult.getRegionMultiplierNNC(c1, c2);
-                candidate->second = nncEntry.trans * mult;
+                candidate->second = nncEntry.trans;
+                if (applyNncMultregT) {
+                    const auto mult = transMult.getRegionMultiplierNNC(c1, c2);
+                    candidate->second *= mult;
+                }
             }
         }
     }