From cd2d81b79acb50429fd72aa83769cfce1f1799a4 Mon Sep 17 00:00:00 2001
From: mattijs <mattijs>
Date: Thu, 3 Oct 2024 16:06:03 +0100
Subject: [PATCH] ENH: extrudePatchMesh: support for features. See #2103

Optional 'featureAngle' entry to disable extrusion on
sharp corners
---
 .../extrudePatchMesh/extrudePatchMesh.C       | 30 +++++++++++++++----
 .../extrudePatchMesh/extrudePatchMesh.H       |  3 ++
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/src/dynamicMesh/extrudePatchMesh/extrudePatchMesh.C b/src/dynamicMesh/extrudePatchMesh/extrudePatchMesh.C
index 1e8a59d802..862758cbcc 100644
--- a/src/dynamicMesh/extrudePatchMesh/extrudePatchMesh.C
+++ b/src/dynamicMesh/extrudePatchMesh/extrudePatchMesh.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2020-2023 OpenCFD Ltd.
+    Copyright (C) 2020-2024 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -33,6 +33,7 @@ License
 #include "wallPolyPatch.H"
 #include "emptyPolyPatch.H"
 #include "wedgePolyPatch.H"
+#include "unitConversion.H"
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
@@ -157,6 +158,12 @@ void Foam::extrudePatchMesh::extrudeMesh(polyPatchList& regionPatches)
     if (this->boundaryMesh().empty())
     {
         const bool columnCells = dict_.get<bool>("columnCells");
+        scalar featAngleCos = -GREAT;
+        scalar featAngle = -1;
+        if (dict_.readIfPresent("featureAngle", featAngle))
+        {
+            featAngleCos = Foam::cos(degToRad(featAngle));
+        }
 
         bitSet nonManifoldEdge(extrudedPatch_.nEdges());
         for (label edgeI = 0; edgeI < extrudedPatch_.nInternalEdges(); edgeI++)
@@ -165,11 +172,24 @@ void Foam::extrudePatchMesh::extrudeMesh(polyPatchList& regionPatches)
             {
                 nonManifoldEdge.set(edgeI);
             }
-            else if (extrudedPatch_.edgeFaces()[edgeI].size() > 2)
+            else
             {
-                // TBD: issue #2780 : non-manifold edges get seen as internal
-                // This bit of code can be removed once #2780 is solved.
-                nonManifoldEdge.set(edgeI);
+                const auto& fcs = extrudedPatch_.edgeFaces()[edgeI];
+                if (fcs.size() > 2)
+                {
+                    // TBD: issue #2780 : non-manifold edges get seen as
+                    // internal.
+                    // This bit of code can be removed once #2780 is solved.
+                    nonManifoldEdge.set(edgeI);
+                }
+                else if (fcs.size() == 2 && featAngleCos >= -1)
+                {
+                    const auto& n = extrudedPatch_.faceNormals();
+                    if ((n[fcs[0]] & n[fcs[1]]) < featAngleCos)
+                    {
+                        nonManifoldEdge.set(edgeI);
+                    }
+                }
             }
         }
 
diff --git a/src/dynamicMesh/extrudePatchMesh/extrudePatchMesh.H b/src/dynamicMesh/extrudePatchMesh/extrudePatchMesh.H
index 5e9130095f..d65baef18f 100644
--- a/src/dynamicMesh/extrudePatchMesh/extrudePatchMesh.H
+++ b/src/dynamicMesh/extrudePatchMesh/extrudePatchMesh.H
@@ -44,6 +44,9 @@ Description
         expansionRatio  1;
         columnCells      true;
 
+        // Optional feature angle to avoid extruding feature-angles
+        featureAngle    45;
+
         // Patch information
         bottomCoeffs
         {