ENH: added clean up function remove0DirFields (RunFunctions)

- less typing than before and avoids relying on bash-specific behaviour
  (fixes #3448)

ENH: add -region support for cleanFaMesh and cleanPolyMesh

CONFIG: add bash completion help for -area-region

ENH: general improvements for regionProperties

- robustness and failsafe for foamListRegions, regionProperties
- additional global model switches for regionModels

applications/utilities/miscellaneous/foamListRegions/foamListRegions.C

@@ -30,7 +30,8 @@ Group
     grpPostProcessingUtilities
 
 Description
-    List regions from constant/regionProperties.
+    List volume regions from constant/regionProperties
+    or area regions from constant/finite-area/regionProperties
 
 Usage
     \b foamListRegions [OPTION]
@@ -72,6 +73,12 @@ int main(int argc, char *argv[])
         "List constant/finite-area/regionProperties (if available)"
     );
 
+    argList::addBoolOption
+    (
+        "optional",
+        "A missing regionProperties is not treated as an error"
+    );
+
     argList::addDryRunOption
     (
         "Make reading optional and add verbosity"
@@ -92,14 +99,20 @@ int main(int argc, char *argv[])
         ++optVerbose;
     }
 
+    // File is optional, not an error
+    const bool isOptional = args.found("optional");
+
     // Use finite-area regions
     const bool doFiniteArea = args.found("finite-area");
 
+    // The number of optional region filters to apply
+    const label nFilters = (args.size()-1);
+
     IOobjectOption::readOption readOpt(IOobjectOption::MUST_READ);
 
-    if (dryRun || doFiniteArea)
+    if (dryRun || isOptional || doFiniteArea)
     {
-        // Always treat finite-area regionProperties as optional
+        // The finite-area regionProperties are also considered optional
         readOpt = IOobjectOption::READ_IF_PRESENT;
     }
 
@@ -116,58 +129,70 @@ int main(int argc, char *argv[])
     if (doFiniteArea)
     {
         regionProps = regionProperties(runTime, faMeshPrefix, readOpt);
-
-        if (regionProps.empty())
-        {
-            InfoErr<< "No finite-area region types" << nl;
-        }
-        else if (optVerbose)
-        {
-            InfoErr
-                << "Have " << regionProps.size()
-                << " finite-area region types, "
-                << regionProps.count() << " regions" << nl << nl;
-        }
     }
     else
     {
         regionProps = regionProperties(runTime, readOpt);
+    }
 
+    // Some reporting...
     if (regionProps.empty())
     {
-            // Probably only occurs with -dry-run option
+        if (doFiniteArea)
+        {
+            InfoErr<< "No finite-area region types" << nl;
+        }
+        else if (isOptional)
+        {
             InfoErr<< "No region types" << nl;
         }
+    }
     else if (optVerbose)
     {
+        InfoErr << "Have " << regionProps.size();
+
+        if (doFiniteArea)
+        {
+            InfoErr<< " finite-area";
+        }
         InfoErr
-                << "Have " << regionProps.size() << " region types, "
+            << " region types, "
             << regionProps.count() << " regions" << nl << nl;
     }
-    }
+
 
     // We now handle checking args and general sanity etc.
-    wordList regionTypes;
 
-    if (args.size() > 1)
+    DynamicList<word> regionTypes;
+
+    if (isOptional && regionProps.empty())
     {
-        regionTypes.resize(args.size()-1);
+        // Nothing to do...
+    }
+    else if (nFilters > 0)
+    {
+        // Apply region filters
 
-        // No duplicates
+        regionTypes.reserve_exact
+        (
+            Foam::min(nFilters, regionProps.size())
+        );
+
+        // No duplicates, and no duplicate warnings
         wordHashSet uniq;
 
-        label nTypes = 0;
         for (label argi = 1; argi < args.size(); ++argi)
         {
-            regionTypes[nTypes] = args[argi];
-
-            const word& regType = regionTypes[nTypes];
+            word regType(args[argi]);
 
             if (uniq.insert(regType))
             {
                 if (regionProps.contains(regType))
                 {
-                    ++nTypes;
+                    if (!regionTypes.contains(regType))
+                    {
+                        regionTypes.push_back(std::move(regType));
+                    }
                 }
                 else
                 {
@@ -175,24 +200,24 @@ int main(int argc, char *argv[])
                 }
             }
         }
-
-        regionTypes.resize(nTypes);
     }
     else
     {
+        // Take all regions
         regionTypes = regionProps.sortedToc();
     }
 
 
     for (const word& regionType : regionTypes)
     {
-        const wordList& regionNames = regionProps[regionType];
-
-        for (const word& regionName : regionNames)
+        if (const auto iter = regionProps.cfind(regionType); iter.good())
+        {
+            for (const word& regionName : iter.val())
             {
                 Info<< regionName << nl;
             }
         }
+    }
 
     return 0;
 }

bin/foamCleanFaMesh

@@ -0,0 +1,138 @@
+#!/bin/sh
+#------------------------------------------------------------------------------
+# =========                 |
+# \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+#  \\    /   O peration     |
+#   \\  /    A nd           | www.openfoam.com
+#    \\/     M anipulation  |
+#-------------------------------------------------------------------------------
+#     Copyright (C) 2011 OpenFOAM Foundation
+#     Copyright (C) 2025 OpenCFD Ltd.
+#------------------------------------------------------------------------------
+# License
+#     This file is part of OpenFOAM, distributed under GPL-3.0-or-later.
+#
+# Script
+#     foamCleanFaMesh
+#
+# Description
+#    Remove the contents of the constant/finite-area/faMesh directory
+#    as per the Foam::faMesh::removeFiles() method.
+#
+#------------------------------------------------------------------------------
+usage() {
+    exec 1>&2
+    while [ "$#" -ge 1 ]; do echo "$1"; shift; done
+    cat <<USAGE
+
+Usage: ${0##*/} [OPTION]
+options:
+  -case <dir>           case directory, default is the cwd
+  -area-region <name>   area-mesh region
+  -dry-run | -n         report actions but do not remove
+  -help                 print the usage
+
+Remove the contents of the constant/finite-area/faMesh directory as per the
+Foam::faMesh::removeFiles() method.
+
+USAGE
+   exit 1
+}
+
+#------------------------------------------------------------------------------
+# Parse options
+unset caseDir areaRegion optDryRun
+
+while [ "$#" -gt 0 ]
+do
+    case "$1" in
+    -h | -help*)
+        usage
+        ;;
+    -dry-run | -n)
+        optDryRun="(dry-run) "
+        ;;
+
+    -case=*)
+        caseDir="${1#*=}"
+        ;;
+
+    -case)
+        [ "$#" -ge 2 ] || usage "'$1' option requires an argument"
+        cd "$2" 2>/dev/null || usage "directory does not exist:  '$2'"
+        caseDir=$2
+        shift
+        ;;
+
+    -area-region)
+        [ "$#" -ge 2 ] || usage "'$1' option requires an argument"
+        areaRegion=$2
+        shift
+        ;;
+
+    (*)
+        usage "unknown option/argument: '$*'"
+        ;;
+    esac
+    shift
+done
+
+#------------------------------------------------------------------------------
+
+# Remove files (mesh etc)
+# also remove .gz versions of the same files
+
+removeFiles()
+{
+    local directory="$1"
+
+    for i in \
+        faceLabels \
+        faBoundary \
+    ;
+    do
+        if [ -n "$optDryRun" ]
+        then
+            echo "${optDryRun} rm -rf $directory/{$i,$i.gz}"
+        else
+            rm -rf -- "$directory/$i" "$directory/$i.gz"
+        fi
+    done
+}
+
+#------------------------------------------------------------------------------
+
+meshDir="constant/finite-area/${areaRegion}${areaRegion:+/}faMesh"
+
+if [ -d "$meshDir" ]
+then
+    # [OK] has constant/finite-areaRegion/<region>/faMesh
+    :
+
+elif [ -n "$caseDir" ]
+then
+    # Specified -case, so no extra magic...
+    echo "Error: no <$meshDir> in $caseDir" 1>&2
+    exit 1
+
+else
+    # Try some other combinations
+    other="${meshDir#constant/}"
+
+    if [ -d "$other" ]
+    then
+        # Probably already within constant/
+        meshDir="$other}"
+    elif [ "${PWD##*/}" = faMesh ] && [ -z "$areaRegion" ]
+    then
+        # Apparently already within faMesh/
+        meshDir=.
+    fi
+fi
+
+
+echo "Cleaning ${caseDir:-.}/$meshDir" 1>&2
+
+removeFiles "$meshDir"
+
+#------------------------------------------------------------------------------

bin/foamCleanPolyMesh

@@ -7,7 +7,7 @@
 #    \\/     M anipulation  |
 #-------------------------------------------------------------------------------
 #     Copyright (C) 2011-2016 OpenFOAM Foundation
-#     Copyright (C) 2022 OpenCFD Ltd.
+#     Copyright (C) 2022,2025 OpenCFD Ltd.
 #------------------------------------------------------------------------------
 # License
 #     This file is part of OpenFOAM, distributed under GPL-3.0-or-later.
@@ -27,8 +27,9 @@ usage() {
 
 Usage: ${0##*/} [OPTION]
 options:
-  -case <dir>       specify alternative case directory, default is the cwd
-  -region <name>    specify alternative mesh region
+  -case <dir>           case directory, default is the cwd
+  -region <name>        mesh region
+  -dry-run | -n         report actions but do not remove
   -help                 print the usage
 
 Remove the contents of the constant/polyMesh directory as per the
@@ -38,58 +39,101 @@ USAGE
    exit 1
 }
 
-unset caseDir regionName
+#------------------------------------------------------------------------------
+# Parse options
+unset caseDir regionName optDryRun
 
-# Parse a single option
 while [ "$#" -gt 0 ]
 do
     case "$1" in
     -h | -help*)
         usage
         ;;
+    -dry-run | -n)
+        optDryRun="(dry-run) "
+        ;;
+
+    -case=*)
+        caseDir="${1#*=}"
+        ;;
+
     -case)
+        caseDir="$2"
         [ "$#" -ge 2 ] || usage "'$1' option requires an argument"
         cd "$2" 2>/dev/null || usage "directory does not exist:  '$2'"
         caseDir=$2
-        shift 2
+        shift
         ;;
+
     -region)
         [ "$#" -ge 2 ] || usage "'$1' option requires an argument"
-        regionName=$2
-        shift 2
+        regionName="$2"
+        shift
         ;;
-    *)
+
+    (*)
         usage "unknown option/argument: '$*'"
         ;;
     esac
+    shift
 done
 
-meshDir=polyMesh
-if [ -n "$regionName" ]
-then
-    meshDir="$regionName/$meshDir"
-fi
+#------------------------------------------------------------------------------
 
-# If -case was specified: insist upon 'constant/polyMesh'
-if [ -n "$caseDir" ]
-then
-    if [ -d constant/"$meshDir" ]
+# Remove files (mesh itself, modifiers, snappyHexMesh ones) and subdirectories
+# also remove .gz versions of the same files
+
+removeFiles()
+{
+    local directory="$1"
+
+    for i in \
+        points faces \
+        owner neighbour \
+        boundary \
+        cells \
+        cellZones faceZones pointZones \
+        meshModifiers \
+        parallelData \
+        sets \
+        cellLevel pointLevel \
+        level0Edge \
+        refinementHistory \
+        surfaceIndex \
+    ;
+    do
+        if [ -n "$optDryRun" ]
         then
-        # Use constant/polyMesh
-        meshDir=constant/"$meshDir"
+            echo "${optDryRun} rm -rf $directory/{$i,$i.gz}"
         else
-       echo "Error: no 'constant/$meshDir' in $caseDir" 1>&2
-       exit 1
+            rm -rf -- "$directory/$i" "$directory/$i.gz"
         fi
-else
-    if [ -d constant/"$meshDir" ]
-    then
-        # Use constant/polyMesh
-        meshDir=constant/"$meshDir"
-    elif [ -d "$meshDir" ]
-    then
-        # Likely already in constant/ - do not adjust anything
+    done
+}
+
+#------------------------------------------------------------------------------
+
+meshDir="constant/${regionName}${regionName:+/}polyMesh"
+
+if [ -d "$meshDir" ]
+then
+    # [OK] has constant/<region>/polyMesh
     :
+
+elif [ -n "$caseDir" ]
+then
+    # Specified -case, so no extra magic...
+    echo "Error: no <$meshDir> in $caseDir" 1>&2
+    exit 1
+
+else
+    # Try some other combinations
+    other="${meshDir#constant/}"
+
+    if [ -d "$other" ]
+    then
+        # Probably already within constant/
+        meshDir="$other}"
     elif [ "${PWD##*/}" = polyMesh ] && [ -z "$regionName" ]
     then
         # Apparently already within polyMesh/
@@ -98,31 +142,8 @@ else
 fi
 
 
-# Remove files (mesh itself, modifiers, snappyHexMesh ones) and subdirectories
-# also remove .gz versions of the same files
 echo "Cleaning ${caseDir:-.}/$meshDir" 1>&2
 
-for i in \
-    points \
-    faces \
-    owner \
-    neighbour \
-    cells \
-    boundary \
-    pointZones \
-    faceZones \
-    cellZones \
-    meshModifiers \
-    parallelData \
-    sets \
-    cellLevel \
-    pointLevel \
-    level0Edge \
-    refinementHistory \
-    surfaceIndex \
-;
-do
-    rm -rf "$meshDir/$i" "$meshDir/$i.gz"
-done
+removeFiles "$meshDir"
 
 #------------------------------------------------------------------------------

bin/tools/CleanFunctions

@@ -108,54 +108,116 @@ cleanPostProcessing()
 }
 
 
+# ---------------
+# Remove constant/finite-area/faMesh or constant/finite-area/{region}/faMesh
+#
+# Accepts following options:
+#   -region <name>      The region name
+#   --                  End of options
+# ---------------
 cleanFaMesh()
 {
-    if [ -e constant/finite-area/faMesh ]
+    local region
+
+    # Parse options
+    while [ "$#" -gt 0 ]
+    do
+        case "$1" in
+        ('')  ;;                # Ignore empty option
+        (--)  shift; break ;;   # Stop option parsing
+
+        (-region)   region="$2"; shift ;;
+        (*) break ;;
+        esac
+        shift
+    done
+
+    # safety
+    if [ "$region" = "--" ]; then unset region; fi
+
+    local meshDir="constant/finite-area/${region}${region:+/}faMesh"
+
+    if [ -e "$meshDir" ]
     then
-        rm -rf constant/finite-area/faMesh
+        [ -n "$region" ] && echo "Clearing $meshDir" 1>&2
+        rm -rf -- "$meshDir"
     fi
-    if [ -e constant/faMesh ]
+
+    # Legacy location <constant/faMesh>
+    # - may still have remnant <constant/faMesh/faMeshDefinition>
+
+    meshDir="constant/faMesh"
+    if [ -e "$meshDir" ] && [ -z "$region" ]
     then
-        if [ -e constant/faMesh/faMeshDefinition ]
+        if [ -e "$meshDir"/faMeshDefinition ]
         then
-            # Old constant/faMesh location for faMeshDefinition still in use:
-            # - warn but don't remove anything
+            # VERY OLD LOCATION
             echo
-            echo "Warning: not removing constant/faMesh/"
+            echo "WARNING: not removing $meshDir/"
             echo "    It contains a 'faMeshDefinition' file"
-            echo "    Please relocate file(s) to system/ !!"
+            echo "    Please relocate file(s) to system/finite-area/ !!"
             echo
         else
             # Can remove constant/faMesh/ entirely (no faMeshDefinition)
-            rm -rf constant/faMesh
+            echo "Clearing $meshDir" 1>&2
+            rm -rf -- "$meshDir"
         fi
     fi
 }
 
 
+# ---------------
+# Remove constant/polyMesh or constant/<region>/polyMesh
+#
+# Accepts following options:
+#   -region <name>      The region name
+#   --                  End of options
+# ---------------
 cleanPolyMesh()
 {
-    if [ -e constant/polyMesh ]
+    local region
+
+    # Parse options
+    while [ "$#" -gt 0 ]
+    do
+        case "$1" in
+        ('')  ;;                # Ignore empty option
+        (--)  shift; break ;;   # Stop option parsing
+
+        (-region)   region="$2"; shift ;;
+        (*) break ;;
+        esac
+        shift
+    done
+
+    # safety
+    if [ "$region" = "--" ]; then unset region; fi
+
+    local meshDir="constant/${region}${region:+/}polyMesh"
+
+    if [ -e "$meshDir" ]
     then
-        if [ -e constant/polyMesh/blockMeshDict ] \
-        || [ -e constant/polyMesh/blockMeshDict.m4 ]
+        [ -n "$region" ] && echo "Clearing $meshDir" 1>&2
+
+        if [ -e "$meshDir"/blockMeshDict ] \
+        || [ -e "$meshDir"/blockMeshDict.m4 ]
         then
-            # Old constant/polyMesh location for blockMeshDict still in use:
-            # - warn but don't remove anything
+            # VERY OLD LOCATION
             echo
-            echo "Warning: not removing constant/polyMesh/"
+            echo "WARNING: not removing $meshDir/"
             echo "    It contains a 'blockMeshDict' or 'blockMeshDict.m4' file"
             echo "    Please relocate file(s) to system/ !!"
             echo
         else
             # Can remove constant/polyMesh/ entirely (no blockMeshDict)
-            rm -rf constant/polyMesh
+            rm -rf -- "$meshDir"
         fi
     fi
 
-    if [ -e system/blockMeshDict.m4 ]
+    meshDir="system${region:+/}${region}"
+    if [ -e "$meshDir"/blockMeshDict.m4 ]
     then
-        rm -f system/blockMeshDict
+        rm -f -- "$meshDir"/blockMeshDict
     fi
 }
 
@@ -212,7 +274,7 @@ cleanCase0()
 removeCase()
 {
     echo "Removing case ${1:-unknown}"
-    [ "$#" -ge 1 ] && rm -rf "$1"
+    [ "$#" -ge 1 ] && rm -rf -- "$1"
 }
 
 

bin/tools/RunFunctions

@@ -517,9 +517,11 @@ cloneParallelCase()
 }
 
 
+# ---------------
 # If 0.orig/ exists, copy (overwrite) into 0/ [ie, serial case]
 # * -processor : copy into processor directories instead
 # * -all : copy into serial and processor directories
+# ---------------
 restore0Dir()
 {
     if [ ! -d 0.orig ]
@@ -553,4 +555,61 @@ restore0Dir()
 }
 
 
+# ---------------
+# Helper routine to remove specified fields from the 0/ directory.
+# Often used in combination with foamListRegions.
+#
+# Accepts following options:
+#   -region <name>      The region name
+#   --                  End of options
+#
+# any remaining parameters are taken to be fields names
+# ---------------
+remove0DirFields()
+{
+    local region
+
+    # Parse options
+    while [ "$#" -gt 0 ]
+    do
+        case "$1" in
+        ('')  ;;                # Ignore empty option
+        (--)  shift; break ;;   # Stop option parsing
+
+        (-region)   region="$2"; shift ;;
+        (*) break ;;
+        esac
+        shift
+    done
+
+    # safety
+    if [ "$region" = "--" ]; then unset region; fi
+
+    if [ "$#" -eq 0 ]
+    then
+        echo "No fields specified for ${region:+region=$region }" 1>&2
+        return 0
+    fi
+
+    echo "Remove 0/ fields${region:+ [$region]} : $@" 1>&2
+
+    local subdir
+    for subdir in 0/"$region" processor*/0/"$region"
+    do
+        if [ -d "$subdir" ]
+        then
+            for field in $@  ## unquoted for IFS splitting [SIC]
+            do
+                # Cautious with removal
+                if [ -f "$subdir/$field" ]
+                then
+                    rm -f -- "$subdir/$field"
+                fi
+            done
+        fi
+    done
+    return 0
+}
+
+
 #------------------------------------------------------------------------------

etc/config.sh/bash_completion

@@ -140,6 +140,11 @@ _of_complete_()
         # Could use "foamListTimes -withZero", but still doesn't address ranges
         COMPREPLY=($(compgen -d -X '![-0-9]*' -- ${cur}))
         ;;
+    -area-region)
+        # Or: $(find system/finite-area -mindepth 1 -maxdepth 1 -type d 2>/dev/null | sed -e 's%.*/%%')
+        choices=$(\ls -d system/finite-area/*/ 2>/dev/null | sed -e 's%/$%%; s%^.*/%%')
+        COMPREPLY=($(compgen -W "$choices" -- ${cur}))
+        ;;
     -region)
         # Or: $(find system -mindepth 1 -maxdepth 1 -type d 2>/dev/null | sed -e 's%.*/%%')
         choices=$(\ls -d system/*/ 2>/dev/null | sed -e 's%/$%%; s%^.*/%%')

src/meshTools/Make/files

@@ -351,7 +351,8 @@ $(vtk)/topoSet/foamVtkWriteFaceSet.C
 $(vtk)/topoSet/foamVtkWritePointSet.C
 $(vtk)/topoSet/foamVtkWriteCellSetFaces.C
 
-regionModel/regionProperties/regionProperties.C
+regionModel/regionProperties/regionProperties.cxx
+regionModel/regionProperties/regionModelProperties.cxx
 
 tetOverlapVolume/tetOverlapVolume.C
 

src/meshTools/regionModel/regionProperties/regionModelProperties.cxx

@@ -0,0 +1,49 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2025 OpenCFD Ltd.
+-------------------------------------------------------------------------------
+License
+    This file is part of OpenFOAM.
+
+    OpenFOAM 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.
+
+    OpenFOAM 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 OpenFOAM.  If not, see <http://www.gnu.org/licenses/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "regionProperties.H"
+
+// * * * * * * * * * * * * * * * Global Functions  * * * * * * * * * * * * * //
+
+// The enable/disable flag for allowFaModels()
+static bool allowFaModels_ = true;
+
+bool Foam::regionModels::allowFaModels() noexcept
+{
+    return allowFaModels_;
+}
+
+
+bool Foam::regionModels::allowFaModels(bool on) noexcept
+{
+    bool old(allowFaModels_);
+    allowFaModels_ = on;
+    return old;
+}
+
+
+// ************************************************************************* //

src/meshTools/regionModel/regionProperties/regionProperties.H

@@ -46,18 +46,39 @@ Description
     \endverbatim
 
 SourceFiles
-    regionProperties.C
+    regionProperties.cxx
+    regionModelProperties.cxx
 
 \*---------------------------------------------------------------------------*/
 
 #ifndef Foam_regionProperties_H
 #define Foam_regionProperties_H
 
-#include "HashTable.H"
 #include "fileName.H"
 #include "wordList.H"
+#include "HashTable.H"
 #include "IOobjectOption.H"
 
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+// General controls
+
+namespace Foam
+{
+namespace regionModels
+{
+
+//- The enable/disable state for regionFaModel (default: true)
+bool allowFaModels() noexcept;
+
+//- Set enable/disable state for regionFaModel
+//  \return previous state
+bool allowFaModels(bool on) noexcept;
+
+} // End namespace regionModels
+} // End namespace Foam
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 namespace Foam
@@ -119,6 +140,17 @@ public:
     ~regionProperties() = default;
 
 
+    // Static Member Functions
+
+        //- The expected search path (eg, constant/regionProperties).
+        //  Can be useful when generation error messages
+        static fileName objectRelPath
+        (
+            const Time& runTime,
+            const fileName& local = fileName::null
+        );
+
+
     // Member Functions
 
         //- Total count of all region names.

src/meshTools/regionModel/regionProperties/regionProperties.cxx

@@ -31,6 +31,21 @@ License
 #include "Time.H"
 #include "wordRes.H"
 
+// * * * * * * * * * * * * * Static Member Functions * * * * * * * * * * * * //
+
+Foam::fileName Foam::regionProperties::objectRelPath
+(
+    const Time& runTime,
+    const fileName& local
+)
+{
+    return
+    (
+        runTime.time().constant()/local/"regionProperties"
+    );
+}
+
+
 // * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
 
 Foam::regionProperties::regionProperties
@@ -56,6 +71,18 @@ Foam::regionProperties::regionProperties
         )
     );
 
+    // For optional reading:
+    // - applies to the file and its overall contents.
+    // - if read and has content, "regions" becomes mandatory
+
+    if (IOobjectOption::isReadOptional(rOpt))
+    {
+        if (iodict.hasHeaderClass() && !iodict.empty())
+        {
+            rOpt = IOobjectOption::MUST_READ;
+        }
+    }
+
     iodict.readEntry("regions", props, keyType::LITERAL, rOpt);
 }
 

tutorials/basic/chtMultiRegionFoam/2DImplicitCyclic/Allmesh

@@ -13,10 +13,11 @@ restore0Dir
 runApplication splitMeshRegions -cellZones -overwrite
 
 # Remove fluid fields from solid regions (important for post-processing)
+fields="nut alphat epsilon k U p_rgh"
+
 for region in $(foamListRegions solid)
 do
-    rm -f 0/$region/{nut,alphat,epsilon,k,U,p_rgh}
-    rm -f processor*/0/$region/{nut,alphat,epsilon,k,U,p_rgh}
+    remove0DirFields -region "$region" -- $fields
 done
 
 for region in $(foamListRegions)

tutorials/heatTransfer/chtMultiRegionFoam/externalCoupledHeater/Allrun.pre

@@ -12,10 +12,11 @@ restore0Dir
 runApplication splitMeshRegions -cellZones -overwrite
 
 # Remove fluid fields from solid regions (important for post-processing)
+fields="nut alphat epsilon k U p_rgh"
+
 for region in $(foamListRegions solid)
 do
-    rm -f 0/$region/{nut,alphat,epsilon,k,U,p_rgh}
-    rm -f processor*/0/$region/{nut,alphat,epsilon,k,U,p_rgh}
+    remove0DirFields -region "$region" -- $fields
 done
 
 for region in $(foamListRegions)

tutorials/heatTransfer/chtMultiRegionFoam/externalSolarLoad/Allrun.pre

@@ -11,10 +11,11 @@ runApplication splitMeshRegions -cellZones -overwrite
 rm -rf 0/domain3 constant/domain3 system/domain3
 
 # Remove fluid fields from solid regions (important for post-processing)
+fields="rho nut alphat epsilon k U p_rgh qr G IDefault"
+
 for region in $(foamListRegions solid)
 do
-    rm -f 0/$region/{rho,nut,alphat,epsilon,k,U,p_rgh,qr,G,IDefault}
-    rm -f processor*/0/$region/{rho,nut,alphat,epsilon,k,U,p_rgh,qr,G,IDefault}
+    remove0DirFields -region "$region" -- $fields
 done
 
 # Set the initial fields

tutorials/heatTransfer/chtMultiRegionFoam/multiRegionHeater/Allrun.pre

@@ -12,10 +12,11 @@ restore0Dir
 runApplication splitMeshRegions -cellZones -overwrite
 
 # Remove fluid fields from solid regions (important for post-processing)
+fields="nut alphat epsilon k U p_rgh"
+
 for region in $(foamListRegions solid)
 do
-    rm -f 0/$region/{nut,alphat,epsilon,k,U,p_rgh}
-    rm -f processor*/0/$region/{nut,alphat,epsilon,k,U,p_rgh}
+    remove0DirFields -region "$region" -- $fields
 done
 
 for region in $(foamListRegions)

tutorials/heatTransfer/chtMultiRegionFoam/snappyMultiRegionHeater/Allrun-parallel

@@ -26,10 +26,11 @@ restore0Dir -processor
 runParallel $decompDict splitMeshRegions -cellZones -overwrite
 
 # Remove fluid fields from solid regions (important for post-processing)
+fields="nut alphat epsilon k U p_rgh"
+
 for region in $(foamListRegions solid)
 do
-    rm -f 0/"$region"/{nut,alphat,epsilon,k,U,p_rgh}
-    rm -f processor*/0/"$region"/{nut,alphat,epsilon,k,U,p_rgh}
+    remove0DirFields -region "$region" -- $fields
 done
 
 for region in $(foamListRegions)

tutorials/heatTransfer/chtMultiRegionFoam/snappyMultiRegionHeater/Allrun-serial

@@ -21,10 +21,11 @@ restore0Dir
 runApplication splitMeshRegions -cellZones -overwrite
 
 # Remove fluid fields from solid regions (important for post-processing)
+fields="nut alphat epsilon k U p_rgh"
+
 for region in $(foamListRegions solid)
 do
-    rm -f 0/"$region"/{nut,alphat,epsilon,k,U,p_rgh}
-    rm -f processor*/0/"$region"/{nut,alphat,epsilon,k,U,p_rgh}
+    remove0DirFields -region "$region" -- $fields
 done
 
 for region in $(foamListRegions)

tutorials/heatTransfer/chtMultiRegionFoam/snappyMultiRegionHeaterImplicit/Allrun

@@ -32,10 +32,11 @@ restore0Dir -processor
 runParallel $decompDict splitMeshRegions -cellZones -overwrite
 
 # Remove fluid fields from solid regions (important for post-processing)
+fields="nut alphat epsilon k U p_rgh"
+
 for region in $(foamListRegions solid)
 do
-    rm -f 0/$region/{nut,alphat,epsilon,k,U,p_rgh}
-    rm -f processor*/0/$region/{nut,alphat,epsilon,k,U,p_rgh}
+    remove0DirFields -region "$region" -- $fields
 done
 
 for region in $(foamListRegions)

tutorials/heatTransfer/chtMultiRegionFoam/solarBeamWithTrees/Allrun.pre

@@ -13,10 +13,11 @@ runApplication splitMeshRegions -cellZones -overwrite
 rm -rf 0/domain3 constant/domain3 system/domain3
 
 # Remove fluid fields from solid regions (important for post-processing)
+fields="rho nut alphat epsilon k U p_rgh qr G IDefault"
+
 for region in $(foamListRegions solid)
 do
-    rm -f 0/"$region"/{rho,nut,alphat,epsilon,k,U,p_rgh,qr,G,IDefault}
-    rm -f processor*/0/"$region"/{rho,nut,alphat,epsilon,k,U,p_rgh,qr,G,IDefault}
+    remove0DirFields -region "$region" -- $fields
 done
 
 # Set the initial fields

tutorials/heatTransfer/chtMultiRegionSimpleFoam/externalCoupledHeater/Allrun.pre

@@ -13,10 +13,11 @@ restore0Dir
 runApplication splitMeshRegions -cellZones -overwrite
 
 # Remove fluid fields from solid regions (important for post-processing)
+fields="nut alphat epsilon k U p_rgh"
+
 for region in $(foamListRegions solid)
 do
-    rm -f 0/"$region"/{nut,alphat,epsilon,k,U,p_rgh}
-    rm -f processor*/0/"$region"/{nut,alphat,epsilon,k,U,p_rgh}
+    remove0DirFields -region "$region" -- $fields
 done
 
 for region in $(foamListRegions)

tutorials/heatTransfer/chtMultiRegionSimpleFoam/multiRegionHeaterRadiation/Allrun.pre

@@ -13,10 +13,11 @@ restore0Dir
 runApplication splitMeshRegions -cellZones -overwrite
 
 # Remove fluid fields from solid regions (important for post-processing)
+fields="rho nut alphat epsilon k U p_rgh qr G IDefault"
+
 for region in $(foamListRegions solid)
 do
-    rm -f 0/"$region"/{rho,nut,alphat,epsilon,k,U,p_rgh,qr,G,IDefault}
-    rm -f processor*/0/"$region"/{rho,nut,alphat,epsilon,k,U,p_rgh,qr,G,IDefault}
+    remove0DirFields -region "$region" -- $fields
 done
 
 for region in $(foamListRegions)