From 075c358fb902cb38e0fbe5ba171c28a89d065449 Mon Sep 17 00:00:00 2001
From: Chris Greenshields <https://cfd.direct>
Date: Tue, 22 Aug 2023 16:48:11 +0100
Subject: [PATCH] snappyHexMeshConfig: layers can be specified for individual
 surfaces

---
 .../snappyHexMeshConfig/snappyHexMeshConfig.C | 21 ++++++----
 .../snappyHexMeshConfiguration.C              | 38 ++++++++++++-------
 .../snappyHexMeshConfiguration.H              |  6 +--
 3 files changed, 42 insertions(+), 23 deletions(-)

diff --git a/applications/utilities/preProcessing/snappyHexMeshConfig/snappyHexMeshConfig.C b/applications/utilities/preProcessing/snappyHexMeshConfig/snappyHexMeshConfig.C
index 8616cd2b22..c005214a11 100644
--- a/applications/utilities/preProcessing/snappyHexMeshConfig/snappyHexMeshConfig.C
+++ b/applications/utilities/preProcessing/snappyHexMeshConfig/snappyHexMeshConfig.C
@@ -86,8 +86,8 @@ Description
     '-refinementBoxes' for quick, box-shaped refinement regions specified by min
     and max bounds; '-refinementDists' for distance-based refinement; and
     '-nCellsBetweenLevels' to control the transition between refinement
-    levels. A '-layers' option specifies additional layers of cells at wall
-    boundaries. The insidePoint parameter is set to '(0 0 0)' by default but can
+    levels. A '-layers' option controls additional layers of cells at specified
+    surfaces. The insidePoint parameter is set to '(0 0 0)' by default but can
     be overridden using the '-insidePoint' option.
 
 Usage
@@ -137,8 +137,8 @@ Usage
       - \par -explicitFeatures,
         Use explicit feature capturing, default is implicit
 
-      - \par -layers \<int\>
-        Specify <int> surface layers at wall boundaries, default 0
+      - \par -layers \<entry\>
+        Number of layers on specified surfaces, e.g. '((car 3) (ground 4))'
 
       - \par -firstLayerThickness \<value\>
         Specify the thickness of the near wall cells for layer addition
@@ -322,8 +322,8 @@ int main(int argc, char *argv[])
     argList::addOption
     (
         "layers",
-        "int",
-        "specify <int> surface layers at wall boundaries, default 0"
+        "entry",
+        "number of layers on specified surfaces, e.g. '((car 3) (ground 4))'"
     );
 
     argList::addOption
@@ -592,7 +592,14 @@ int main(int argc, char *argv[])
 
     const bool explicitFeatures(args.optionFound("explicitFeatures"));
 
-    const label layers(args.optionLookupOrDefault<label>("layers", 0));
+    List<Tuple2<word, label>> layers;
+    if (args.optionFound("layers"))
+    {
+        layers.append
+        (
+            args.optionReadList<Tuple2<word, label>>("layers")
+        );
+    }
 
     const scalar firstLayerThickness
     (
diff --git a/applications/utilities/preProcessing/snappyHexMeshConfig/snappyHexMeshConfiguration.C b/applications/utilities/preProcessing/snappyHexMeshConfig/snappyHexMeshConfiguration.C
index 96693fa19f..58de1021f2 100644
--- a/applications/utilities/preProcessing/snappyHexMeshConfig/snappyHexMeshConfiguration.C
+++ b/applications/utilities/preProcessing/snappyHexMeshConfig/snappyHexMeshConfiguration.C
@@ -37,7 +37,7 @@ void Foam::snappyHexMeshConfiguration::writeSnappySwitches()
     dict.add
     (
         "addLayers",
-        layers_ == 0 ? "off" : "on",
+        layers_.empty() ? "off" : "on",
         true
     );
 
@@ -439,21 +439,33 @@ void Foam::snappyHexMeshConfiguration::writeAddLayersControls()
 
     beginDict(os_, "layers");
 
-    forAll(surfaces_, i)
+    if (layers_.empty())
     {
-        switch (surfaces_[i].type())
+        // Add convenient entries with zero layers if layers are switched off.
+        forAll(surfaces_, i)
         {
-            case surfaceType::wall:
-            case surfaceType::external:
-            case surfaceType::baffle:
+            switch (surfaces_[i].type())
             {
-                os_ << indent << "\"" << surfaces_[i].name()
-                    << ".*\" { nSurfaceLayers "
-                    << layers_ << "; }" << endl;
-                break;
+                case surfaceType::wall:
+                case surfaceType::external:
+                case surfaceType::baffle:
+                {
+                    os_ << indent << "\"" << surfaces_[i].name()
+                        << ".*\" { nSurfaceLayers 0; }" << endl;
+                    break;
+                }
+                default: break;
             }
-
-            default: break;
+        }
+    }
+    else
+    {
+        // Add entries for specified surfaces.
+        forAll(layers_, i)
+        {
+            os_ << indent << "\"" << layers_[i].first()
+                << ".*\" { nSurfaceLayers "
+                << layers_[i].second() << "; }" << endl;
         }
     }
 
@@ -521,7 +533,7 @@ Foam::snappyHexMeshConfiguration::snappyHexMeshConfiguration
     const List<Tuple3<vector, vector, label>>& refinementBoxes,
     const List<Tuple3<word, scalar, label>>& refinementDists,
     const bool explicitFeatures,
-    const label layers,
+    const List<Tuple2<word, label>>& layers,
     const scalar firstLayerThickness,
     const scalar layerExpansionRatio,
     const point& insidePoint,
diff --git a/applications/utilities/preProcessing/snappyHexMeshConfig/snappyHexMeshConfiguration.H b/applications/utilities/preProcessing/snappyHexMeshConfig/snappyHexMeshConfiguration.H
index be5c421730..e15cb35ec1 100644
--- a/applications/utilities/preProcessing/snappyHexMeshConfig/snappyHexMeshConfiguration.H
+++ b/applications/utilities/preProcessing/snappyHexMeshConfig/snappyHexMeshConfiguration.H
@@ -83,8 +83,8 @@ class snappyHexMeshConfiguration
         //- Using explicit feature capturing?
         const bool explicitFeatures_;
 
-        //- Number of layers at wall patches, default 0
-        const label layers_;
+        //- Number of layers on specified surfaces
+        const List<Tuple2<word, label>> layers_;
 
         //- Thickness of the near wall cells with layer addition
         const scalar firstLayerThickness_;
@@ -180,7 +180,7 @@ public:
             const List<Tuple3<vector, vector, label>>& refinementBoxes,
             const List<Tuple3<word, scalar, label>>& refinementDists,
             const bool explicitFeatures,
-            const label layers,
+            const List<Tuple2<word, label>>& layers,
             const scalar firstLayerThickness,
             const scalar layerExpansionRatio,
             const point& insidePoint,