From 320e70af1d2f0a66b707f730657d2507677e3442 Mon Sep 17 00:00:00 2001
From: Will Bainbridge <http://cfd.direct>
Date: Fri, 13 Jan 2023 09:19:08 +0000
Subject: [PATCH] mappedPatchBase: Add "samePatch" option

This option means that a one field can be mapped to another within the
same patch without specifying the patch name. E.g.:

    walls
    {
        type            mappedValue;

        //neighbourPatch  walls; // <-- Previously required. Still supported.

        samePatch       yes;     // <-- New alternative specification

        field           T.liquid;
        value           $internalField;
    }

This is useful when the boundary condition is specified using a regular
expression for the patch name.

    "wall_.*"
    {
        type            mappedValue;

        //neighbourPatch  ???;   // <-- No unique name can be given

        samePatch       yes;     // <-- Still works

        field           T.liquid;
        value           $internalField;
    }
---
 .../mappedPatchBase/mappedPatchBase.C         | 44 ++++++++++++-------
 .../multiphaseEuler/Grossetete/0/T.gas        |  2 +-
 2 files changed, 28 insertions(+), 18 deletions(-)

diff --git a/src/meshTools/mappedPatches/mappedPatchBase/mappedPatchBase.C b/src/meshTools/mappedPatches/mappedPatchBase/mappedPatchBase.C
index 6830d23fe4..a0f2177e99 100644
--- a/src/meshTools/mappedPatches/mappedPatchBase/mappedPatchBase.C
+++ b/src/meshTools/mappedPatches/mappedPatchBase/mappedPatchBase.C
@@ -354,20 +354,17 @@ Foam::mappedPatchBase::mappedPatchBase
     coupleGroup_(dict),
     nbrRegionName_
     (
-        dict.lookupOrDefaultBackwardsCompatible<word>
+        coupleGroup_.valid() ? word::null
+      : dict.lookupOrDefaultBackwardsCompatible<word>
         (
             {"neighbourRegion", "sampleRegion"},
-            coupleGroup_.valid() ? word::null : pp.boundaryMesh().mesh().name()
+            pp.boundaryMesh().mesh().name()
         )
     ),
     nbrPatchName_
     (
-        coupleGroup_.valid()
-      ? dict.lookupOrDefaultBackwardsCompatible<word>
-        (
-            {"neighbourPatch", "samplePatch"},
-            word::null
-        )
+        coupleGroup_.valid() ? word::null
+      : dict.lookupOrDefault<bool>("samePatch", false) ? pp.name()
       : dict.lookupBackwardsCompatible<word>({"neighbourPatch", "samplePatch"})
     ),
     transform_
@@ -392,15 +389,27 @@ Foam::mappedPatchBase::mappedPatchBase
     ),
     matchTol_(dict.lookupOrDefault("matchTolerance", defaultMatchTol_))
 {
-    if
-    (
-        coupleGroup_.valid()
-     && (nbrRegionName_ != word::null || nbrPatchName_ != word::null)
-    )
+    const bool haveCoupleGroup = coupleGroup_.valid();
+
+    const bool haveNbrRegion =
+        dict.found("neighbourRegion") || dict.found("sampleRegion");
+    const bool haveNbrPatch =
+        dict.found("neighbourPatch") || dict.found("samplePatch");
+
+    const bool isSamePatch = dict.lookupOrDefault<bool>("samePatch", false);
+
+    if ((haveNbrRegion || haveNbrPatch || isSamePatch) && haveCoupleGroup)
     {
         FatalIOErrorInFunction(dict)
-            << "Either a coupleGroup or a neighbourRegion/Patch should be "
-            << "specified, not both" << exit(FatalIOError);
+            << "Either neighbourRegion/Patch information or a coupleGroup "
+            << "should be specified, not both" << exit(FatalIOError);
+    }
+
+    if (haveNbrPatch && isSamePatch)
+    {
+        FatalIOErrorInFunction(dict)
+            << "Either a neighbourPatch should be specified, or samePatch "
+            << "should be set to true, not both" << exit(FatalIOError);
     }
 }
 
@@ -493,11 +502,12 @@ void Foam::mappedPatchBase::clearOut()
 bool Foam::mappedPatchBase::specified(const dictionary& dict)
 {
     return
-        dict.found("neighbourRegion")
+        dict.found("coupleGroup")
+     || dict.found("neighbourRegion")
      || dict.found("sampleRegion")
      || dict.found("neighbourPatch")
      || dict.found("samplePatch")
-     || dict.found("coupleGroup");
+     || dict.found("samePatch");
 }
 
 
diff --git a/tutorials/modules/multiphaseEuler/Grossetete/0/T.gas b/tutorials/modules/multiphaseEuler/Grossetete/0/T.gas
index 6db81fec14..be70a06fa9 100644
--- a/tutorials/modules/multiphaseEuler/Grossetete/0/T.gas
+++ b/tutorials/modules/multiphaseEuler/Grossetete/0/T.gas
@@ -35,7 +35,7 @@ boundaryField
     walls
     {
         type            mappedValue;
-        neighbourPatch  walls;
+        samePatch       yes;
         field           T.liquid;
         value           $internalField;
     }