diff --git a/applications/solvers/finiteArea/liquidFilmFoam/createFaFields.H b/applications/solvers/finiteArea/liquidFilmFoam/createFaFields.H
index f269ea0e65..0b4e94b2ca 100644
--- a/applications/solvers/finiteArea/liquidFilmFoam/createFaFields.H
+++ b/applications/solvers/finiteArea/liquidFilmFoam/createFaFields.H
@@ -5,7 +5,7 @@
         (
             "h",
             runTime.timeName(),
-            mesh,
+            aMesh.thisDb(),
             IOobject::MUST_READ,
             IOobject::AUTO_WRITE
         ),
@@ -20,7 +20,7 @@
         (
             "Us",
             runTime.timeName(),
-            mesh,
+            aMesh.thisDb(),
             IOobject::MUST_READ,
             IOobject::AUTO_WRITE
         ),
@@ -34,7 +34,7 @@
         (
             "phis",
             runTime.timeName(),
-            mesh,
+            aMesh.thisDb(),
             IOobject::READ_IF_PRESENT,
             IOobject::AUTO_WRITE
         ),
@@ -48,7 +48,7 @@
         (
             "phi2s",
             runTime.timeName(),
-            mesh,
+            aMesh.thisDb(),
             IOobject::READ_IF_PRESENT,
             IOobject::AUTO_WRITE
         ),
@@ -67,7 +67,7 @@
         (
             "Sm",
             runTime.timeName(),
-            mesh,
+            aMesh.thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -82,7 +82,7 @@
         (
             "Sd",
             runTime.timeName(),
-            mesh,
+            aMesh.thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -96,7 +96,7 @@
         (
             "Sg",
             runTime.timeName(),
-            mesh,
+            aMesh.thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -112,7 +112,7 @@
         (
             "ps",
             runTime.timeName(),
-            mesh,
+            aMesh.thisDb(),
             IOobject::NO_READ,
             IOobject::AUTO_WRITE
         ),
@@ -134,7 +134,7 @@
         (
             "manningField",
             runTime.timeName(),
-            mesh,
+            aMesh.thisDb(),
             IOobject::MUST_READ,
             IOobject::AUTO_WRITE
         ),
@@ -147,7 +147,7 @@
         (
             "frictionFactor",
             runTime.timeName(),
-            mesh,
+            aMesh.thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
diff --git a/applications/solvers/finiteArea/liquidFilmFoam/createFvFields.H b/applications/solvers/finiteArea/liquidFilmFoam/createFvFields.H
index f1260da95f..12b9a34fcc 100644
--- a/applications/solvers/finiteArea/liquidFilmFoam/createFvFields.H
+++ b/applications/solvers/finiteArea/liquidFilmFoam/createFvFields.H
@@ -7,7 +7,7 @@ volVectorField U
     (
         "U",
         runTime.timeName(),
-        mesh,
+        mesh.thisDb(),
         IOobject::NO_READ,
         IOobject::AUTO_WRITE
     ),
@@ -22,7 +22,7 @@ volScalarField H
     (
         "H",
         runTime.timeName(),
-        mesh,
+        mesh.thisDb(),
         IOobject::NO_READ,
         IOobject::AUTO_WRITE
     ),
diff --git a/applications/solvers/finiteArea/sphereSurfactantFoam/createFaFields.H b/applications/solvers/finiteArea/sphereSurfactantFoam/createFaFields.H
index 514c6157d4..87cb736128 100644
--- a/applications/solvers/finiteArea/sphereSurfactantFoam/createFaFields.H
+++ b/applications/solvers/finiteArea/sphereSurfactantFoam/createFaFields.H
@@ -5,7 +5,7 @@ areaScalarField Cs
     (
         "Cs",
         runTime.timeName(),
-        mesh,
+        aMesh.thisDb(),
         IOobject::MUST_READ,
         IOobject::AUTO_WRITE
     ),
@@ -26,7 +26,7 @@ areaVectorField Us
     (
         "Us",
         runTime.timeName(),
-        mesh,
+        aMesh.thisDb(),
         IOobject::NO_READ,
         IOobject::NO_WRITE
     ),
@@ -58,7 +58,7 @@ edgeScalarField phis
     (
         "phis",
         runTime.timeName(),
-        mesh,
+        aMesh.thisDb(),
         IOobject::NO_READ,
         IOobject::NO_WRITE
     ),
diff --git a/applications/solvers/finiteArea/sphereSurfactantFoam/createFaMesh.H b/applications/solvers/finiteArea/sphereSurfactantFoam/createFaMesh.H
deleted file mode 100644
index 905c8e7405..0000000000
--- a/applications/solvers/finiteArea/sphereSurfactantFoam/createFaMesh.H
+++ /dev/null
@@ -1,2 +0,0 @@
-    // Create Finite Area mesh
-    faMesh aMesh(mesh);
diff --git a/applications/solvers/finiteArea/sphereSurfactantFoam/createVolFields.H b/applications/solvers/finiteArea/sphereSurfactantFoam/createVolFields.H
index b06ebaecb8..1661341bd7 100644
--- a/applications/solvers/finiteArea/sphereSurfactantFoam/createVolFields.H
+++ b/applications/solvers/finiteArea/sphereSurfactantFoam/createVolFields.H
@@ -7,7 +7,7 @@
         (
             "Cvf",
             runTime.timeName(),
-            mesh,
+            mesh.thisDb(),
             IOobject::NO_READ,
             IOobject::AUTO_WRITE
         ),
@@ -24,7 +24,7 @@
         (
             "U",
             runTime.timeName(),
-            mesh,
+            mesh.thisDb(),
             IOobject::NO_READ,
             IOobject::AUTO_WRITE
         ),
diff --git a/applications/solvers/finiteArea/surfactantFoam/createFaFields.H b/applications/solvers/finiteArea/surfactantFoam/createFaFields.H
index cb90fd6c63..acbdc61da9 100644
--- a/applications/solvers/finiteArea/surfactantFoam/createFaFields.H
+++ b/applications/solvers/finiteArea/surfactantFoam/createFaFields.H
@@ -5,7 +5,7 @@ areaScalarField Cs
     (
         "Cs",
         runTime.timeName(),
-        mesh,
+        aMesh.thisDb(),
         IOobject::MUST_READ,
         IOobject::AUTO_WRITE
     ),
@@ -37,7 +37,7 @@ areaVectorField Us
     (
         "Us",
         runTime.timeName(),
-        mesh,
+        aMesh.thisDb(),
         IOobject::MUST_READ,
         IOobject::NO_WRITE
     ),
@@ -51,7 +51,7 @@ edgeScalarField phis
     (
         "phis",
         runTime.timeName(),
-        mesh,
+        aMesh.thisDb(),
         IOobject::NO_READ,
         IOobject::NO_WRITE
     ),
diff --git a/applications/solvers/finiteArea/surfactantFoam/createFaMesh.H b/applications/solvers/finiteArea/surfactantFoam/createFaMesh.H
deleted file mode 100644
index 905c8e7405..0000000000
--- a/applications/solvers/finiteArea/surfactantFoam/createFaMesh.H
+++ /dev/null
@@ -1,2 +0,0 @@
-    // Create Finite Area mesh
-    faMesh aMesh(mesh);
diff --git a/applications/solvers/finiteArea/surfactantFoam/createVolFields.H b/applications/solvers/finiteArea/surfactantFoam/createVolFields.H
index ea071e6f62..f17a09f5a0 100644
--- a/applications/solvers/finiteArea/surfactantFoam/createVolFields.H
+++ b/applications/solvers/finiteArea/surfactantFoam/createVolFields.H
@@ -7,7 +7,7 @@
         (
             "Cvf",
             runTime.timeName(),
-            mesh,
+            mesh.thisDb(),
             IOobject::NO_READ,
             IOobject::AUTO_WRITE
         ),
@@ -24,7 +24,7 @@
         (
             "U",
             runTime.timeName(),
-            mesh,
+            mesh.thisDb(),
             IOobject::NO_READ,
             IOobject::AUTO_WRITE
         ),
diff --git a/applications/utilities/parallelProcessing/redistributePar/parFaFieldDistributorCache.C b/applications/utilities/parallelProcessing/redistributePar/parFaFieldDistributorCache.C
index 6aa040c4c9..7810e571ff 100644
--- a/applications/utilities/parallelProcessing/redistributePar/parFaFieldDistributorCache.C
+++ b/applications/utilities/parallelProcessing/redistributePar/parFaFieldDistributorCache.C
@@ -106,30 +106,30 @@ void Foam::parFaFieldDistributorCache::read
         runTime.processorCase(false);
     }
 
-    IOobjectList objects;   //(mesh.mesh(), runTime.timeName());
+    IOobjectList objects;
 
     if (readHandler)
     {
         auto oldHandler = fileOperation::fileHandler(readHandler);
         const auto oldComm = UPstream::commWorld(fileHandler().comm());
 
-        objects = IOobjectList(mesh.mesh(), runTime.timeName());
+        objects = IOobjectList(mesh.thisDb(), runTime.timeName());
         readHandler = fileOperation::fileHandler(oldHandler);
         UPstream::commWorld(oldComm);
     }
 
 
-    if (Pstream::master() && decompose)
+    if (UPstream::master() && decompose)
     {
         runTime.caseName() = proc0CaseName;
         runTime.processorCase(oldProcCase);
     }
 
     Info<< "From time " << runTime.timeName()
-        << " mesh:" << mesh.mesh().objectRegistry::objectRelPath()
+        << " mesh:" << mesh.thisDb().objectRelPath()
         << " have objects:" << objects.names() << endl;
 
-    if (Pstream::master() && decompose)
+    if (UPstream::master() && decompose)
     {
         runTime.caseName() = baseRunTime.caseName();
         runTime.processorCase(false);
diff --git a/src/dynamicFaMesh/interfaceTrackingFvMesh/surfactantProperties.H b/src/dynamicFaMesh/interfaceTrackingFvMesh/surfactantProperties.H
index 47e997fec7..3d02013f3d 100644
--- a/src/dynamicFaMesh/interfaceTrackingFvMesh/surfactantProperties.H
+++ b/src/dynamicFaMesh/interfaceTrackingFvMesh/surfactantProperties.H
@@ -184,7 +184,7 @@ public:
                 (
                     "dSigma",
                     surfactConc.mesh().time().timeName(),
-                    surfactConc.mesh().mesh(),
+                    surfactConc.mesh().thisDb(),
                     IOobject::NO_READ,
                     IOobject::NO_WRITE
                 ),
diff --git a/src/faOptions/faceSetOption/faceSetOption.H b/src/faOptions/faceSetOption/faceSetOption.H
index 3d53f37ab8..8c79b3d567 100644
--- a/src/faOptions/faceSetOption/faceSetOption.H
+++ b/src/faOptions/faceSetOption/faceSetOption.H
@@ -100,7 +100,6 @@ SourceFiles
 
 #include "faOption.H"
 #include "faceSet.H"
-#include "faMesh.H"
 #include "Time.H"
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/faOptions/sources/derived/externalFileSource/externalFileSource.C b/src/faOptions/sources/derived/externalFileSource/externalFileSource.C
index a1d2333616..bece83706d 100644
--- a/src/faOptions/sources/derived/externalFileSource/externalFileSource.C
+++ b/src/faOptions/sources/derived/externalFileSource/externalFileSource.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2022 OpenCFD Ltd.
+    Copyright (C) 2019-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -61,8 +61,8 @@ Foam::fa::externalFileSource::externalFileSource
         IOobject
         (
             "pExt",
-            mesh_.time().timeName(),
-            mesh_,
+            regionMesh().thisDb().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE,
             (
@@ -150,7 +150,7 @@ bool Foam::fa::externalFileSource::read(const dictionary& dict)
         const labelList& patches = regionMesh().whichPolyPatches();
 
         mapping_.clear();
-        mapping_.resize(patches.empty() ? 0 : (patches.last()+1));
+        mapping_.resize(patches.empty() ? 0 : (patches.back()+1));
 
         for (const label patchi : patches)
         {
diff --git a/src/faOptions/sources/derived/jouleHeatingSource/jouleHeatingSource.C b/src/faOptions/sources/derived/jouleHeatingSource/jouleHeatingSource.C
index 0de1a2276e..051cd3d7b8 100644
--- a/src/faOptions/sources/derived/jouleHeatingSource/jouleHeatingSource.C
+++ b/src/faOptions/sources/derived/jouleHeatingSource/jouleHeatingSource.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2022 OpenCFD Ltd.
+    Copyright (C) 2019-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -151,10 +151,12 @@ void Foam::fa::jouleHeatingSource::addSup
 
         tmp<areaScalarField> tsource;
 
+        const auto& obr = regionMesh().thisDb();
+
         if (anisotropicElectricalConductivity_)
         {
             const auto& sigma =
-                mesh_.lookupObject<areaTensorField>
+                obr.lookupObject<areaTensorField>
                 (
                     typeName + ":sigma_" + regionName_
                 );
@@ -164,7 +166,7 @@ void Foam::fa::jouleHeatingSource::addSup
         else
         {
             const auto& sigma =
-                mesh_.lookupObject<areaScalarField>
+                obr.lookupObject<areaScalarField>
                 (
                     typeName + ":sigma_" + regionName_
                 );
diff --git a/src/faOptions/sources/derived/jouleHeatingSource/jouleHeatingSourceTemplates.C b/src/faOptions/sources/derived/jouleHeatingSource/jouleHeatingSourceTemplates.C
index 2216b0b6a3..a59bdc65ac 100644
--- a/src/faOptions/sources/derived/jouleHeatingSource/jouleHeatingSourceTemplates.C
+++ b/src/faOptions/sources/derived/jouleHeatingSource/jouleHeatingSourceTemplates.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2020 OpenCFD Ltd.
+    Copyright (C) 2019-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -38,6 +38,8 @@ void Foam::fa::jouleHeatingSource::initialiseSigma
 {
     typedef GeometricField<Type, faPatchField, areaMesh> AreaFieldType;
 
+    auto& obr = regionMesh().thisDb();
+
     if (dict.found("sigma"))
     {
         // Sigma to be defined using a Function1 type
@@ -48,8 +50,8 @@ void Foam::fa::jouleHeatingSource::initialiseSigma
             IOobject
             (
                 typeName + ":sigma_" + regionName_,
-                mesh_.time().timeName(),
-                mesh_,
+                obr.time().timeName(),
+                obr,
                 IOobject::NO_READ,
                 IOobject::AUTO_WRITE
             ),
@@ -57,7 +59,7 @@ void Foam::fa::jouleHeatingSource::initialiseSigma
             dimensioned<Type>(sqr(dimCurrent)/dimPower/dimLength, Zero)
         );
 
-        mesh_.objectRegistry::store(tsigma.ptr());
+        regIOobject::store(tsigma.ptr());
 
         Info<< "    Conductivity 'sigma' read from dictionary as f(T)"
             << nl << endl;
@@ -70,15 +72,15 @@ void Foam::fa::jouleHeatingSource::initialiseSigma
             IOobject
             (
                 typeName + ":sigma_" + regionName_,
-                mesh().time().timeName(),
-                mesh(),
+                obr.time().timeName(),
+                obr,
                 IOobject::MUST_READ,
                 IOobject::AUTO_WRITE
             ),
             regionMesh()
         );
 
-        mesh().objectRegistry::store(tsigma.ptr());
+        regIOobject::store(tsigma.ptr());
 
         Info<< "    Conductivity 'sigma' read from file" << nl << endl;
     }
@@ -94,11 +96,10 @@ Foam::fa::jouleHeatingSource::updateSigma
 {
     typedef GeometricField<Type, faPatchField, areaMesh> AreaFieldType;
 
+    const auto& obr = regionMesh().thisDb();
+
     auto& sigma =
-        mesh().lookupObjectRef<AreaFieldType>
-        (
-            typeName + ":sigma_" + regionName_
-        );
+        obr.lookupObjectRef<AreaFieldType>(typeName + ":sigma_" + regionName_);
 
     if (!sigmaVsTPtr)
     {
@@ -106,7 +107,7 @@ Foam::fa::jouleHeatingSource::updateSigma
         return sigma;
     }
 
-    const auto& T = mesh().lookupObject<areaScalarField>(TName_);
+    const auto& T = obr.lookupObject<areaScalarField>(TName_);
 
     // Internal field
     forAll(sigma, i)
diff --git a/src/finiteArea/faMesh/faGlobalMeshData/faGlobalMeshData.C b/src/finiteArea/faMesh/faGlobalMeshData/faGlobalMeshData.C
index d83324d1b0..7c401d6742 100644
--- a/src/finiteArea/faMesh/faGlobalMeshData/faGlobalMeshData.C
+++ b/src/finiteArea/faMesh/faGlobalMeshData/faGlobalMeshData.C
@@ -73,17 +73,18 @@ const Foam::faMesh& Foam::faGlobalMeshData::mesh() const noexcept
 
 void Foam::faGlobalMeshData::updateMesh()
 {
-    label polyMeshNGlobalPoints = mesh_().globalData().nGlobalPoints();
+    // The polyMesh globalMeshData
+    const globalMeshData& pData = mesh_.mesh().globalData();
 
     const labelList& polyMeshSharedPointLabels =
-        mesh_().globalData().sharedPointLabels();
+        pData.sharedPointLabels();
 
     const labelList& polyMeshSharedPointAddr =
-        mesh_().globalData().sharedPointAddr();
+        pData.sharedPointAddr();
 
     labelHashSet sharedPointLabels;
 
-    labelField globalList(polyMeshNGlobalPoints, Zero);
+    labelField globalList(pData.nGlobalPoints(), Zero);
 
     forAll(mesh_.boundary(), patchI)
     {
diff --git a/src/finiteArea/faMesh/faMesh.C b/src/finiteArea/faMesh/faMesh.C
index da2c40492d..7a0efb3f9f 100644
--- a/src/finiteArea/faMesh/faMesh.C
+++ b/src/finiteArea/faMesh/faMesh.C
@@ -790,7 +790,7 @@ void Foam::faMesh::removeFiles(const fileName& instanceDir) const
 
 void Foam::faMesh::removeFiles() const
 {
-    removeFiles(mesh().instance());
+    removeFiles(thisDb().instance());
 }
 
 
diff --git a/src/finiteArea/faMesh/faMesh.H b/src/finiteArea/faMesh/faMesh.H
index 4d9c779350..ebe866b5c7 100644
--- a/src/finiteArea/faMesh/faMesh.H
+++ b/src/finiteArea/faMesh/faMesh.H
@@ -628,9 +628,6 @@ public:
         //- Return access to polyMesh
         inline const polyMesh& mesh() const;
 
-        //- Interface to referenced polyMesh (similar to GeoMesh)
-        const polyMesh& operator()() const { return mesh(); }
-
         //- Return the local mesh directory (dbDir()/meshSubDir)
         fileName meshDir() const;
 
@@ -965,6 +962,12 @@ public:
         bool operator!=(const faMesh& m) const;
 
         bool operator==(const faMesh& m) const;
+
+
+    // Housekeeping
+
+        //- No call operator. Prior to 2312 was used to obtain polyMesh
+        void operator()() const = delete;
 };
 
 
diff --git a/src/finiteArea/faMesh/faMeshMapper/faAreaMapper.C b/src/finiteArea/faMesh/faMeshMapper/faAreaMapper.C
index 3f179bc6b7..e079de2bab 100644
--- a/src/finiteArea/faMesh/faMeshMapper/faAreaMapper.C
+++ b/src/finiteArea/faMesh/faMeshMapper/faAreaMapper.C
@@ -61,10 +61,10 @@ void Foam::faAreaMapper::calcAddressing() const
 
     // Prepare a list of new face labels and (preliminary) addressing
     // Note: dimensioned to number of boundary faces of polyMesh
-    newFaceLabelsPtr_ = new labelList(mesh_().nBoundaryFaces(), -1);
+    newFaceLabelsPtr_ = new labelList(mesh_.mesh().nBoundaryFaces(), -1);
     labelList& newFaceLabels = *newFaceLabelsPtr_;
 
-    newFaceLabelsMapPtr_ = new labelList(mesh_().nBoundaryFaces(), -1);
+    newFaceLabelsMapPtr_ = new labelList(mesh_.mesh().nBoundaryFaces(), -1);
     labelList& newFaceLabelsMap = *newFaceLabelsMapPtr_;
     label nNewFaces = 0;
 
diff --git a/src/finiteArea/faMesh/faMeshPatches.C b/src/finiteArea/faMesh/faMeshPatches.C
index 91708caa1a..6cf01d2a62 100644
--- a/src/finiteArea/faMesh/faMeshPatches.C
+++ b/src/finiteArea/faMesh/faMeshPatches.C
@@ -434,7 +434,7 @@ Foam::faPatchList Foam::faMesh::createPatchList
                 (
                     patch(),
                     selectEdges,
-                    mesh().time().globalPath(),
+                    thisDb().time().globalPath(),
                     outputName
                 );
 
@@ -517,7 +517,7 @@ Foam::faPatchList Foam::faMesh::createPatchList
                 (
                     patch(),
                     selectEdges,
-                    mesh().time().globalPath(),
+                    thisDb().time().globalPath(),
                     outputName
                 );
 
diff --git a/src/finiteArea/faMesh/faMeshTopology.C b/src/finiteArea/faMesh/faMeshTopology.C
index 8453514639..9c85727b5a 100644
--- a/src/finiteArea/faMesh/faMeshTopology.C
+++ b/src/finiteArea/faMesh/faMeshTopology.C
@@ -199,7 +199,7 @@ Foam::faMesh::getBoundaryEdgeConnections() const
             (
                 patch(),
                 selectEdges,
-                mesh().time().globalPath(),
+                thisDb().time().globalPath(),
                 outputName
             );
 
@@ -348,7 +348,7 @@ Foam::faMesh::getBoundaryEdgeConnections() const
             (
                 patch(),
                 selectEdges,
-                mesh().time().globalPath(),
+                thisDb().time().globalPath(),
                 outputName
             );
 
@@ -711,7 +711,7 @@ Foam::faMesh::getBoundaryEdgeConnections() const
         (
             cpp,
             selectEdges,
-            mesh().time().globalPath(),
+            thisDb().time().globalPath(),
             outputName
         );
 
@@ -743,7 +743,7 @@ Foam::faMesh::getBoundaryEdgeConnections() const
                 patch().boundaryEdges(),
                 fileName
                 (
-                    mesh().time().globalPath()
+                    thisDb().time().globalPath()
                   / ("faMesh-construct.boundaryEdges")
                 )
             );
@@ -776,7 +776,7 @@ Foam::faMesh::getBoundaryEdgeConnections() const
                 patch(),
                 fileName
                 (
-                    mesh().time().globalPath()
+                    thisDb().time().globalPath()
                   / ("faMesh-construct.faPatch")
                 )
             );
@@ -799,7 +799,7 @@ Foam::faMesh::getBoundaryEdgeConnections() const
         (
             patch(),
             selectEdges,
-            mesh().time().globalPath(),
+            thisDb().time().globalPath(),
             outputName
         );
 
@@ -915,7 +915,7 @@ void Foam::faMesh::setBoundaryConnections
         (
             patch(),
             selectEdges,
-            mesh().time().globalPath(),
+            thisDb().time().globalPath(),
             outputName
         );
 
diff --git a/src/finiteArea/faMesh/faPatches/constraint/wedge/wedgeFaPatch.C b/src/finiteArea/faMesh/faPatches/constraint/wedge/wedgeFaPatch.C
index d24c3d3790..c6dc075505 100644
--- a/src/finiteArea/faMesh/faPatches/constraint/wedge/wedgeFaPatch.C
+++ b/src/finiteArea/faMesh/faPatches/constraint/wedge/wedgeFaPatch.C
@@ -98,7 +98,7 @@ Foam::wedgeFaPatch::wedgeFaPatch
 
     const auto* wedgePtr = isA<wedgePolyPatch>
     (
-        bm.mesh()().boundaryMesh()[ngbPolyPatchIndex()]
+        bm.mesh().mesh().boundaryMesh()[ngbPolyPatchIndex()]
     );
 
     if (wedgePtr)
diff --git a/src/finiteArea/interpolation/edgeInterpolation/schemes/NVDscheme/faNVDscheme.H b/src/finiteArea/interpolation/edgeInterpolation/schemes/NVDscheme/faNVDscheme.H
index 67270a7f12..b6ad35709a 100644
--- a/src/finiteArea/interpolation/edgeInterpolation/schemes/NVDscheme/faNVDscheme.H
+++ b/src/finiteArea/interpolation/edgeInterpolation/schemes/NVDscheme/faNVDscheme.H
@@ -119,7 +119,7 @@ public:
             NVDweight(is),
             edgeFlux_
             (
-                mesh().objectRegistry::lookupObject<edgeScalarField>
+                mesh.thisDb().lookupObject<edgeScalarField>
                 (
                     word(is)
                 )
diff --git a/src/finiteArea/interpolation/edgeInterpolation/schemes/blended/blendedEdgeInterpolation.H b/src/finiteArea/interpolation/edgeInterpolation/schemes/blended/blendedEdgeInterpolation.H
index 41f3636176..5e3bfc513a 100644
--- a/src/finiteArea/interpolation/edgeInterpolation/schemes/blended/blendedEdgeInterpolation.H
+++ b/src/finiteArea/interpolation/edgeInterpolation/schemes/blended/blendedEdgeInterpolation.H
@@ -106,7 +106,7 @@ public:
             upwindEdgeInterpolation<Type>
             (
                 mesh,
-                mesh().objectRegistry::lookupObject<edgeScalarField>
+                mesh.thisDb().lookupObject<edgeScalarField>
                 (
                     word(is)
                 )
diff --git a/src/finiteArea/interpolation/edgeInterpolation/schemes/upwind/upwindEdgeInterpolation.H b/src/finiteArea/interpolation/edgeInterpolation/schemes/upwind/upwindEdgeInterpolation.H
index df84af7a6d..7384f19d5e 100644
--- a/src/finiteArea/interpolation/edgeInterpolation/schemes/upwind/upwindEdgeInterpolation.H
+++ b/src/finiteArea/interpolation/edgeInterpolation/schemes/upwind/upwindEdgeInterpolation.H
@@ -97,7 +97,7 @@ public:
             edgeInterpolationScheme<Type>(mesh),
             faceFlux_
             (
-                mesh().objectRegistry::lookupObject<edgeScalarField>
+                mesh.thisDb().lookupObject<edgeScalarField>
                 (
                     word(is)
                 )
diff --git a/src/regionFaModels/KirchhoffShell/KirchhoffShell.C b/src/regionFaModels/KirchhoffShell/KirchhoffShell.C
index cef06db82b..1b09200a93 100644
--- a/src/regionFaModels/KirchhoffShell/KirchhoffShell.C
+++ b/src/regionFaModels/KirchhoffShell/KirchhoffShell.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2021 OpenCFD Ltd.
+    Copyright (C) 2019-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -151,8 +151,8 @@ KirchhoffShell::KirchhoffShell
         IOobject
         (
             "ps_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::READ_IF_PRESENT,
             IOobject::NO_WRITE
         ),
@@ -164,8 +164,8 @@ KirchhoffShell::KirchhoffShell
         IOobject
         (
             "h_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::MUST_READ,
             IOobject::AUTO_WRITE
         ),
@@ -176,8 +176,8 @@ KirchhoffShell::KirchhoffShell
         IOobject
         (
             "laplaceW_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -189,8 +189,8 @@ KirchhoffShell::KirchhoffShell
         IOobject
         (
             "laplace2W_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -202,8 +202,8 @@ KirchhoffShell::KirchhoffShell
         IOobject
         (
             "w0_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -215,8 +215,8 @@ KirchhoffShell::KirchhoffShell
         IOobject
         (
             "w00_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -228,8 +228,8 @@ KirchhoffShell::KirchhoffShell
         IOobject
         (
             "laplaceW0_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -241,8 +241,8 @@ KirchhoffShell::KirchhoffShell
         IOobject
         (
             "laplace2W0_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -289,8 +289,8 @@ const tmp<areaScalarField> KirchhoffShell::rho() const
             IOobject
             (
                 "rhos",
-                primaryMesh().time().timeName(),
-                primaryMesh(),
+                regionMesh().time().timeName(),
+                regionMesh().thisDb(),
                 IOobject::NO_READ,
                 IOobject::NO_WRITE,
                 IOobject::NO_REGISTER
diff --git a/src/regionFaModels/liquidFilm/liquidFilmBase.C b/src/regionFaModels/liquidFilm/liquidFilmBase.C
index d2b1c78ccc..afe3dc40a0 100644
--- a/src/regionFaModels/liquidFilm/liquidFilmBase.C
+++ b/src/regionFaModels/liquidFilm/liquidFilmBase.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2020-2022 OpenCFD Ltd.
+    Copyright (C) 2020-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -90,8 +90,8 @@ liquidFilmBase::liquidFilmBase
         IOobject
         (
             "hf_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::MUST_READ,
             IOobject::AUTO_WRITE
         ),
@@ -103,8 +103,8 @@ liquidFilmBase::liquidFilmBase
         IOobject
         (
             "Uf_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::MUST_READ,
             IOobject::AUTO_WRITE
         ),
@@ -115,8 +115,8 @@ liquidFilmBase::liquidFilmBase
         IOobject
         (
             "pf_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::AUTO_WRITE
         ),
@@ -128,8 +128,8 @@ liquidFilmBase::liquidFilmBase
         IOobject
         (
             "ppf_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -141,8 +141,8 @@ liquidFilmBase::liquidFilmBase
         IOobject
         (
             "phif_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::READ_IF_PRESENT,
             IOobject::AUTO_WRITE
         ),
@@ -154,22 +154,21 @@ liquidFilmBase::liquidFilmBase
         IOobject
         (
             "phi2s_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::READ_IF_PRESENT,
             IOobject::AUTO_WRITE
         ),
         fac::interpolate(h_*Uf_) & regionMesh().Le()
     ),
 
-
     gn_
     (
         IOobject
         (
             "gn",
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -185,7 +184,7 @@ liquidFilmBase::liquidFilmBase
         (
             "massSource",
             primaryMesh().time().timeName(),
-            primaryMesh()
+            primaryMesh().thisDb()
         ),
         primaryMesh(),
         dimensionedScalar(dimMass, Zero)
@@ -197,7 +196,7 @@ liquidFilmBase::liquidFilmBase
         (
             "momentumSource",
             primaryMesh().time().timeName(),
-            primaryMesh()
+            primaryMesh().thisDb()
         ),
         primaryMesh(),
         dimensionedVector(dimPressure, Zero)
@@ -209,7 +208,7 @@ liquidFilmBase::liquidFilmBase
         (
             "pnSource",
             primaryMesh().time().timeName(),
-            primaryMesh()
+            primaryMesh().thisDb()
         ),
         primaryMesh(),
         dimensionedScalar(dimPressure, Zero)
@@ -221,7 +220,7 @@ liquidFilmBase::liquidFilmBase
         (
             "energySource",
             primaryMesh().time().timeName(),
-            primaryMesh()
+            primaryMesh().thisDb()
         ),
         primaryMesh(),
         dimensionedScalar(dimEnergy, Zero)
@@ -284,8 +283,8 @@ Foam::tmp<Foam::areaVectorField> liquidFilmBase::Uw() const
             IOobject
             (
                 "tUw",
-                primaryMesh().time().timeName(),
-                primaryMesh()
+                regionMesh().time().timeName(),
+                regionMesh().thisDb()
             ),
             regionMesh(),
             dimensionedVector(dimVelocity, Zero)
@@ -339,8 +338,8 @@ Foam::tmp<Foam::areaVectorField> liquidFilmBase::Us() const
             IOobject
             (
                 "tUs",
-                primaryMesh().time().timeName(),
-                primaryMesh()
+                regionMesh().time().timeName(),
+                regionMesh().thisDb()
             ),
             regionMesh(),
             dimensionedVector(dimVelocity, Zero)
@@ -366,8 +365,8 @@ Foam::tmp<Foam::areaVectorField> liquidFilmBase::Up() const
             IOobject
             (
                 "tUp",
-                primaryMesh().time().timeName(),
-                primaryMesh()
+                regionMesh().time().timeName(),
+                regionMesh().thisDb()
             ),
             regionMesh(),
             dimensionedVector(dimVelocity, Zero)
@@ -414,8 +413,8 @@ tmp<areaScalarField> liquidFilmBase::pg() const
             IOobject
             (
                 "tpg",
-                primaryMesh().time().timeName(),
-                primaryMesh()
+                regionMesh().time().timeName(),
+                regionMesh().thisDb()
             ),
             regionMesh(),
             dimensionedScalar(dimPressure, Zero)
@@ -447,8 +446,8 @@ tmp<areaScalarField> liquidFilmBase::alpha() const
             IOobject
             (
                 "talpha",
-                primaryMesh().time().timeName(),
-                primaryMesh()
+                regionMesh().time().timeName(),
+                regionMesh().thisDb()
             ),
             regionMesh(),
             dimensionedScalar(dimless, Zero)
diff --git a/src/regionFaModels/liquidFilm/liquidFilmModel/liquidFilmModel.C b/src/regionFaModels/liquidFilm/liquidFilmModel/liquidFilmModel.C
index cb4f11c297..1aa3078a31 100644
--- a/src/regionFaModels/liquidFilm/liquidFilmModel/liquidFilmModel.C
+++ b/src/regionFaModels/liquidFilm/liquidFilmModel/liquidFilmModel.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2020-2022 OpenCFD Ltd.
+    Copyright (C) 2020-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -99,8 +99,8 @@ liquidFilmModel::liquidFilmModel
         IOobject
         (
             "rhof",
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::AUTO_WRITE
         ),
@@ -112,8 +112,8 @@ liquidFilmModel::liquidFilmModel
         IOobject
         (
             "muf",
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -125,8 +125,8 @@ liquidFilmModel::liquidFilmModel
         IOobject
         (
             "Tf_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::READ_IF_PRESENT,
             IOobject::AUTO_WRITE
         ),
@@ -138,8 +138,8 @@ liquidFilmModel::liquidFilmModel
         IOobject
         (
             "Cp_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -151,8 +151,8 @@ liquidFilmModel::liquidFilmModel
         IOobject
         (
             "sigmaf",
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -164,8 +164,8 @@ liquidFilmModel::liquidFilmModel
         IOobject
         (
             h_.name() + "*" + rho_.name(),
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -177,8 +177,8 @@ liquidFilmModel::liquidFilmModel
         IOobject
         (
             "rhoSp",
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -190,8 +190,10 @@ liquidFilmModel::liquidFilmModel
         IOobject
         (
             "USp",
-            primaryMesh().time().timeName(),
-            primaryMesh()
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
+            IOobject::NO_READ,
+            IOobject::NO_WRITE
         ),
         regionMesh(),
         dimensionedVector(sqr(dimVelocity), Zero)
@@ -201,8 +203,10 @@ liquidFilmModel::liquidFilmModel
         IOobject
         (
             "pnSp",
-            primaryMesh().time().timeName(),
-            primaryMesh()
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
+            IOobject::NO_READ,
+            IOobject::NO_WRITE
         ),
         regionMesh(),
         dimensionedScalar(dimPressure, Zero)
@@ -213,7 +217,7 @@ liquidFilmModel::liquidFilmModel
         (
             "cloudMassTrans",
             primaryMesh().time().timeName(),
-            primaryMesh(),
+            primaryMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -227,7 +231,7 @@ liquidFilmModel::liquidFilmModel
         (
             "cloudDiameterTrans",
             primaryMesh().time().timeName(),
-            primaryMesh(),
+            primaryMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
diff --git a/src/regionFaModels/liquidFilm/subModels/kinematic/filmTurbulenceModel/filmTurbulenceModel/filmTurbulenceModel.C b/src/regionFaModels/liquidFilm/subModels/kinematic/filmTurbulenceModel/filmTurbulenceModel/filmTurbulenceModel.C
index f89cb18063..a6c8b42f4a 100644
--- a/src/regionFaModels/liquidFilm/subModels/kinematic/filmTurbulenceModel/filmTurbulenceModel/filmTurbulenceModel.C
+++ b/src/regionFaModels/liquidFilm/subModels/kinematic/filmTurbulenceModel/filmTurbulenceModel/filmTurbulenceModel.C
@@ -108,8 +108,8 @@ tmp<areaScalarField> filmTurbulenceModel::Cw() const
             IOobject
             (
                 "tCw",
-                film_.primaryMesh().time().timeName(),
-                film_.primaryMesh()
+                film_.regionMesh().time().timeName(),
+                film_.regionMesh().thisDb()
             ),
             film_.regionMesh(),
             dimensionedScalar(dimVelocity)
@@ -272,8 +272,8 @@ tmp<faVectorMatrix> filmTurbulenceModel::primaryRegionFriction
                 IOobject
                 (
                     "taForce",
-                    film_.primaryMesh().time().timeName(),
-                    film_.primaryMesh()
+                    film_.regionMesh().time().timeName(),
+                    film_.regionMesh().thisDb()
                 ),
                 film_.regionMesh(),
                 dimensionedVector(sqr(dimVelocity), Zero)
diff --git a/src/regionFaModels/liquidFilm/subModels/kinematic/filmTurbulenceModel/laminar/laminar.C b/src/regionFaModels/liquidFilm/subModels/kinematic/filmTurbulenceModel/laminar/laminar.C
index 7859246570..20b764f3dd 100644
--- a/src/regionFaModels/liquidFilm/subModels/kinematic/filmTurbulenceModel/laminar/laminar.C
+++ b/src/regionFaModels/liquidFilm/subModels/kinematic/filmTurbulenceModel/laminar/laminar.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2020-2021 OpenCFD Ltd.
+    Copyright (C) 2020-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -64,8 +64,8 @@ tmp<areaScalarField> laminar::mut() const
         IOobject
         (
             "mut",
-            film().primaryMesh().time().timeName(),
-            film().primaryMesh(),
+            film().regionMesh().time().timeName(),
+            film().regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
diff --git a/src/regionFaModels/liquidFilm/subModels/kinematic/force/contactAngleForces/contactAngleForce/contactAngleForce.C b/src/regionFaModels/liquidFilm/subModels/kinematic/force/contactAngleForces/contactAngleForce/contactAngleForce.C
index 5dc0e4b8d1..dfe9dad388 100644
--- a/src/regionFaModels/liquidFilm/subModels/kinematic/force/contactAngleForces/contactAngleForce/contactAngleForce.C
+++ b/src/regionFaModels/liquidFilm/subModels/kinematic/force/contactAngleForces/contactAngleForce/contactAngleForce.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2020-2022 OpenCFD Ltd.
+    Copyright (C) 2020-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -68,8 +68,8 @@ tmp<faVectorMatrix> contactAngleForce::correct(areaVectorField& U)
         IOobject
         (
             IOobject::scopedName(typeName, "contactForce"),
-            film().primaryMesh().time().timeName(),
-            film().primaryMesh(),
+            film().regionMesh().time().timeName(),
+            film().regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE,
             IOobject::NO_REGISTER
diff --git a/src/regionFaModels/liquidFilm/subModels/kinematic/force/contactAngleForces/dynamicContactAngleForce/dynamicContactAngleForce.C b/src/regionFaModels/liquidFilm/subModels/kinematic/force/contactAngleForces/dynamicContactAngleForce/dynamicContactAngleForce.C
index 4119e50a98..559dbab3b7 100644
--- a/src/regionFaModels/liquidFilm/subModels/kinematic/force/contactAngleForces/dynamicContactAngleForce/dynamicContactAngleForce.C
+++ b/src/regionFaModels/liquidFilm/subModels/kinematic/force/contactAngleForces/dynamicContactAngleForce/dynamicContactAngleForce.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2020-2022 OpenCFD Ltd.
+    Copyright (C) 2020-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -105,8 +105,8 @@ tmp<areaScalarField> dynamicContactAngleForce::theta() const
         IOobject
         (
             IOobject::scopedName(typeName, "theta"),
-            film().primaryMesh().time().timeName(),
-            film().primaryMesh(),
+            film().regionMesh().time().timeName(),
+            film().regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE,
             IOobject::NO_REGISTER
diff --git a/src/regionFaModels/liquidFilm/subModels/kinematic/injectionModel/curvatureSeparation/curvatureSeparation.C b/src/regionFaModels/liquidFilm/subModels/kinematic/injectionModel/curvatureSeparation/curvatureSeparation.C
index 77b628724c..46599c9750 100644
--- a/src/regionFaModels/liquidFilm/subModels/kinematic/injectionModel/curvatureSeparation/curvatureSeparation.C
+++ b/src/regionFaModels/liquidFilm/subModels/kinematic/injectionModel/curvatureSeparation/curvatureSeparation.C
@@ -136,11 +136,11 @@ tmp<scalarField> curvatureSeparation::calcCosAngle
             IOobject
             (
                 "cosAngle",
-                film().primaryMesh().time().timeName(),
-                film().primaryMesh(),
+                mesh.time().timeName(),
+                mesh.thisDb(),
                 IOobject::NO_READ
             ),
-            film().regionMesh(),
+            mesh,
             dimensionedScalar(dimless, Zero)
         );
         volCosAngle.primitiveFieldRef() = cosAngle;
@@ -255,8 +255,8 @@ void curvatureSeparation::correct
             IOobject
             (
                 "Fnet",
-                film().primaryMesh().time().timeName(),
-                film().primaryMesh(),
+                mesh.time().timeName(),
+                mesh.thisDb(),
                 IOobject::NO_READ
             ),
             mesh,
@@ -270,8 +270,8 @@ void curvatureSeparation::correct
             IOobject
             (
                 "separated",
-                film().primaryMesh().time().timeName(),
-                film().primaryMesh(),
+                mesh.time().timeName(),
+                mesh.thisDb(),
                 IOobject::NO_READ
             ),
             mesh,
@@ -285,8 +285,8 @@ void curvatureSeparation::correct
             IOobject
             (
                 "massToInject",
-                film().primaryMesh().time().timeName(),
-                film().primaryMesh(),
+                mesh.time().timeName(),
+                mesh.thisDb(),
                 IOobject::NO_READ
             ),
             mesh,
@@ -300,8 +300,8 @@ void curvatureSeparation::correct
             IOobject
             (
                 "InvR1",
-                film().primaryMesh().time().timeName(),
-                film().primaryMesh(),
+                mesh.time().timeName(),
+                mesh.thisDb(),
                 IOobject::NO_READ
             ),
             mesh,
diff --git a/src/regionFaModels/regionFaModel/regionFaModelI.H b/src/regionFaModels/regionFaModel/regionFaModelI.H
index 8f2f16c74d..7e8a407e7f 100644
--- a/src/regionFaModels/regionFaModel/regionFaModelI.H
+++ b/src/regionFaModels/regionFaModel/regionFaModelI.H
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2022 OpenCFD Ltd.
+    Copyright (C) 2019-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -31,16 +31,11 @@ License
 
 inline const Foam::faMesh& Foam::regionModels::regionFaModel::regionMesh() const
 {
-    auto* regionPtr = time_.getObjectPtr<faMesh>(regionName_);
-
-    if (regionPtr)
-    {
-        return *regionPtr;
-    }
-    else if (!regionMeshPtr_)
+    if (!regionMeshPtr_)
     {
         FatalErrorInFunction
-            << "Region mesh not available" << abort(FatalError);
+            << "Region mesh not available"
+            << abort(FatalError);
     }
 
     return *regionMeshPtr_;
@@ -49,16 +44,11 @@ inline const Foam::faMesh& Foam::regionModels::regionFaModel::regionMesh() const
 
 inline Foam::faMesh& Foam::regionModels::regionFaModel::regionMesh()
 {
-    auto* regionPtr = time_.getObjectPtr<faMesh>(regionName_);
-
-    if (regionPtr)
-    {
-        return *regionPtr;
-    }
-    else if (!regionMeshPtr_)
+    if (!regionMeshPtr_)
     {
         FatalErrorInFunction
-            << "Region mesh not available" << abort(FatalError);
+            << "Region mesh not available"
+            << abort(FatalError);
     }
 
     return *regionMeshPtr_;
diff --git a/src/regionFaModels/thermalShell/thermalShell.C b/src/regionFaModels/thermalShell/thermalShell.C
index 43830c875f..3fa2465dd9 100644
--- a/src/regionFaModels/thermalShell/thermalShell.C
+++ b/src/regionFaModels/thermalShell/thermalShell.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2020 OpenCFD Ltd.
+    Copyright (C) 2019-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -60,17 +60,15 @@ bool thermalShell::init(const dictionary& dict)
 
 tmp<areaScalarField> thermalShell::qr()
 {
-    IOobject io
-    (
-        "tqr",
-        primaryMesh().time().timeName(),
-        primaryMesh()
-    );
-
     auto taqr =
         tmp<areaScalarField>::New
         (
-            io,
+            IOobject
+            (
+                "tqr",
+                regionMesh().time().timeName(),
+                regionMesh().thisDb()
+            ),
             regionMesh(),
             dimensionedScalar(dimPower/dimArea, Zero)
         );
@@ -136,8 +134,8 @@ thermalShell::thermalShell
         IOobject
         (
             "qs_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::READ_IF_PRESENT,
             IOobject::NO_WRITE
         ),
@@ -149,8 +147,8 @@ thermalShell::thermalShell
         IOobject
         (
             "h_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::MUST_READ,
             IOobject::AUTO_WRITE
         ),
@@ -191,8 +189,8 @@ const tmp<areaScalarField> thermalShell::Cp() const
             IOobject
             (
                 "Cps",
-                primaryMesh().time().timeName(),
-                primaryMesh(),
+                regionMesh().time().timeName(),
+                regionMesh().thisDb(),
                 IOobject::NO_READ,
                 IOobject::NO_WRITE,
                 IOobject::NO_REGISTER
@@ -214,8 +212,8 @@ const tmp<areaScalarField> thermalShell::rho() const
             IOobject
             (
                 "rhos",
-                primaryMesh().time().timeName(),
-                primaryMesh(),
+                regionMesh().time().timeName(),
+                regionMesh().thisDb(),
                 IOobject::NO_READ,
                 IOobject::NO_WRITE,
                 IOobject::NO_REGISTER
@@ -237,8 +235,8 @@ const tmp<areaScalarField> thermalShell::kappa() const
             IOobject
             (
                 "kappas",
-                primaryMesh().time().timeName(),
-                primaryMesh(),
+                regionMesh().time().timeName(),
+                regionMesh().thisDb(),
                 IOobject::NO_READ,
                 IOobject::NO_WRITE,
                 IOobject::NO_REGISTER
diff --git a/src/regionFaModels/thermalShellModel/thermalShellModel.C b/src/regionFaModels/thermalShellModel/thermalShellModel.C
index 7c3fa1add8..4e9274a78d 100644
--- a/src/regionFaModels/thermalShellModel/thermalShellModel.C
+++ b/src/regionFaModels/thermalShellModel/thermalShellModel.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2022 OpenCFD Ltd.
+    Copyright (C) 2019-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -60,8 +60,8 @@ thermalShellModel::thermalShellModel
         IOobject
         (
             "Ts_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::MUST_READ,
             IOobject::AUTO_WRITE
         ),
diff --git a/src/regionFaModels/vibrationShellModel/vibrationShellModel.C b/src/regionFaModels/vibrationShellModel/vibrationShellModel.C
index db78812a94..f63bfdee4c 100644
--- a/src/regionFaModels/vibrationShellModel/vibrationShellModel.C
+++ b/src/regionFaModels/vibrationShellModel/vibrationShellModel.C
@@ -5,7 +5,7 @@
     \\  /    A nd           | www.openfoam.com
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
-    Copyright (C) 2019-2022 OpenCFD Ltd.
+    Copyright (C) 2019-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -60,8 +60,8 @@ vibrationShellModel::vibrationShellModel
         IOobject
         (
             "ws_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::MUST_READ,
             IOobject::AUTO_WRITE
         ),
@@ -72,8 +72,8 @@ vibrationShellModel::vibrationShellModel
         IOobject
         (
             "as_" + regionName_,
-            primaryMesh().time().timeName(),
-            primaryMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::AUTO_WRITE
         ),
diff --git a/src/regionModels/surfaceFilmModels/submodels/thermo/filmRadiationModel/constantRadiation/constantRadiation.C b/src/regionModels/surfaceFilmModels/submodels/thermo/filmRadiationModel/constantRadiation/constantRadiation.C
index ecc5ab7bad..04607ad05c 100644
--- a/src/regionModels/surfaceFilmModels/submodels/thermo/filmRadiationModel/constantRadiation/constantRadiation.C
+++ b/src/regionModels/surfaceFilmModels/submodels/thermo/filmRadiationModel/constantRadiation/constantRadiation.C
@@ -64,7 +64,7 @@ constantRadiation::constantRadiation
         (
             typeName + ":qrConst",
             film.time().timeName(),
-            film.regionMesh(),
+            film.regionMesh().thisDb(),
             IOobject::MUST_READ,
             IOobject::AUTO_WRITE
         ),
@@ -76,7 +76,7 @@ constantRadiation::constantRadiation
         (
             typeName + ":mask",
             film.time().timeName(),
-            film.regionMesh(),
+            film.regionMesh().thisDb(),
             IOobject::READ_IF_PRESENT,
             IOobject::AUTO_WRITE
         ),
diff --git a/src/regionModels/surfaceFilmModels/submodels/thermo/filmRadiationModel/noRadiation/noRadiation.C b/src/regionModels/surfaceFilmModels/submodels/thermo/filmRadiationModel/noRadiation/noRadiation.C
index d5c0eaa091..cb934c6708 100644
--- a/src/regionModels/surfaceFilmModels/submodels/thermo/filmRadiationModel/noRadiation/noRadiation.C
+++ b/src/regionModels/surfaceFilmModels/submodels/thermo/filmRadiationModel/noRadiation/noRadiation.C
@@ -81,7 +81,7 @@ tmp<volScalarField> noRadiation::Shs()
         (
             typeName + ":Shs",
             film().time().timeName(),
-            film().regionMesh(),
+            film().regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
diff --git a/src/regionModels/surfaceFilmModels/submodels/thermo/filmRadiationModel/primaryRadiation/primaryRadiation.C b/src/regionModels/surfaceFilmModels/submodels/thermo/filmRadiationModel/primaryRadiation/primaryRadiation.C
index 7e503cbad1..38b2b13e72 100644
--- a/src/regionModels/surfaceFilmModels/submodels/thermo/filmRadiationModel/primaryRadiation/primaryRadiation.C
+++ b/src/regionModels/surfaceFilmModels/submodels/thermo/filmRadiationModel/primaryRadiation/primaryRadiation.C
@@ -64,7 +64,7 @@ primaryRadiation::primaryRadiation
         (
             "qin", // same name as qin on primary region to enable mapping
             film.time().timeName(),
-            film.regionMesh(),
+            film.regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -100,7 +100,7 @@ tmp<volScalarField> primaryRadiation::Shs()
             (
                 typeName + ":Shs",
                 film().time().timeName(),
-                film().regionMesh(),
+                film().regionMesh().thisDb(),
                 IOobject::NO_READ,
                 IOobject::NO_WRITE
             ),
diff --git a/src/regionModels/surfaceFilmModels/submodels/thermo/filmRadiationModel/standardRadiation/standardRadiation.C b/src/regionModels/surfaceFilmModels/submodels/thermo/filmRadiationModel/standardRadiation/standardRadiation.C
index b3c8c375a3..fd39725570 100644
--- a/src/regionModels/surfaceFilmModels/submodels/thermo/filmRadiationModel/standardRadiation/standardRadiation.C
+++ b/src/regionModels/surfaceFilmModels/submodels/thermo/filmRadiationModel/standardRadiation/standardRadiation.C
@@ -65,7 +65,7 @@ standardRadiation::standardRadiation
         (
             "qin", // same name as qin on primary region to enable mapping
             film.time().timeName(),
-            film.regionMesh(),
+            film.regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -79,7 +79,7 @@ standardRadiation::standardRadiation
         (
             "qrNet",
             film.time().timeName(),
-            film.regionMesh(),
+            film.regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
diff --git a/src/regionModels/surfaceFilmModels/submodels/thermo/filmViscosityModel/thixotropicViscosity/thixotropicViscosity.C b/src/regionModels/surfaceFilmModels/submodels/thermo/filmViscosityModel/thixotropicViscosity/thixotropicViscosity.C
index 931b23d3ff..67d8e792b8 100644
--- a/src/regionModels/surfaceFilmModels/submodels/thermo/filmViscosityModel/thixotropicViscosity/thixotropicViscosity.C
+++ b/src/regionModels/surfaceFilmModels/submodels/thermo/filmViscosityModel/thixotropicViscosity/thixotropicViscosity.C
@@ -78,7 +78,7 @@ thixotropicViscosity::thixotropicViscosity
         (
             typeName + ":lambda",
             film.regionMesh().time().timeName(),
-            film.regionMesh(),
+            film.regionMesh().thisDb(),
             IOobject::MUST_READ,
             IOobject::AUTO_WRITE
         ),
diff --git a/src/regionModels/surfaceFilmModels/submodels/thermo/filmViscosityModel/waxSolventViscosity/waxSolventViscosity.C b/src/regionModels/surfaceFilmModels/submodels/thermo/filmViscosityModel/waxSolventViscosity/waxSolventViscosity.C
index 69a1a0e3be..df4c6ab9a8 100644
--- a/src/regionModels/surfaceFilmModels/submodels/thermo/filmViscosityModel/waxSolventViscosity/waxSolventViscosity.C
+++ b/src/regionModels/surfaceFilmModels/submodels/thermo/filmViscosityModel/waxSolventViscosity/waxSolventViscosity.C
@@ -120,7 +120,7 @@ waxSolventViscosity::waxSolventViscosity
         (
             typeName + ":muWax",
             film.regionMesh().time().timeName(),
-            film.regionMesh(),
+            film.regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::AUTO_WRITE
         ),
@@ -143,7 +143,7 @@ waxSolventViscosity::waxSolventViscosity
         (
             typeName + ":muSolvent",
             film.regionMesh().time().timeName(),
-            film.regionMesh(),
+            film.regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::AUTO_WRITE
         ),
diff --git a/src/regionModels/surfaceFilmModels/submodels/thermo/heatTransferModel/constantHeatTransfer/constantHeatTransfer.C b/src/regionModels/surfaceFilmModels/submodels/thermo/heatTransferModel/constantHeatTransfer/constantHeatTransfer.C
index d36ad75b81..9bdae5059c 100644
--- a/src/regionModels/surfaceFilmModels/submodels/thermo/heatTransferModel/constantHeatTransfer/constantHeatTransfer.C
+++ b/src/regionModels/surfaceFilmModels/submodels/thermo/heatTransferModel/constantHeatTransfer/constantHeatTransfer.C
@@ -84,7 +84,7 @@ tmp<volScalarField> constantHeatTransfer::h() const
             (
                 "htc",
                 filmModel_.time().timeName(),
-                filmModel_.regionMesh(),
+                filmModel_.regionMesh().thisDb(),
                 IOobject::NO_READ,
                 IOobject::NO_WRITE,
                 IOobject::NO_REGISTER
diff --git a/src/regionModels/surfaceFilmModels/submodels/thermo/heatTransferModel/mappedConvectiveHeatTransfer/mappedConvectiveHeatTransfer.C b/src/regionModels/surfaceFilmModels/submodels/thermo/heatTransferModel/mappedConvectiveHeatTransfer/mappedConvectiveHeatTransfer.C
index 2453e7a017..3dc85260f2 100644
--- a/src/regionModels/surfaceFilmModels/submodels/thermo/heatTransferModel/mappedConvectiveHeatTransfer/mappedConvectiveHeatTransfer.C
+++ b/src/regionModels/surfaceFilmModels/submodels/thermo/heatTransferModel/mappedConvectiveHeatTransfer/mappedConvectiveHeatTransfer.C
@@ -65,7 +65,7 @@ mappedConvectiveHeatTransfer::mappedConvectiveHeatTransfer
         (
             "htcConv",
             film.time().timeName(),
-            film.primaryMesh(),
+            film.primaryMesh().thisDb(),
             IOobject::MUST_READ,
             IOobject::AUTO_WRITE
         ),
@@ -77,7 +77,7 @@ mappedConvectiveHeatTransfer::mappedConvectiveHeatTransfer
         (
             htcConvPrimary_.name(), // must have same name as above for mapping
             film.time().timeName(),
-            film.regionMesh(),
+            film.regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
diff --git a/src/regionModels/surfaceFilmModels/submodels/thermo/phaseChangeModel/solidification/solidification.C b/src/regionModels/surfaceFilmModels/submodels/thermo/phaseChangeModel/solidification/solidification.C
index d9113f319e..dd7ecd529a 100644
--- a/src/regionModels/surfaceFilmModels/submodels/thermo/phaseChangeModel/solidification/solidification.C
+++ b/src/regionModels/surfaceFilmModels/submodels/thermo/phaseChangeModel/solidification/solidification.C
@@ -77,7 +77,7 @@ solidification::solidification
         (
             typeName + ":mass",
             film.regionMesh().time().timeName(),
-            film.regionMesh(),
+            film.regionMesh().thisDb(),
             IOobject::READ_IF_PRESENT,
             IOobject::AUTO_WRITE
         ),
@@ -91,7 +91,7 @@ solidification::solidification
         (
             typeName + ":thickness",
             film.regionMesh().time().timeName(),
-            film.regionMesh(),
+            film.regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::AUTO_WRITE
         ),
diff --git a/src/regionModels/surfaceFilmModels/submodels/thermo/phaseChangeModel/waxSolventEvaporation/waxSolventEvaporation.C b/src/regionModels/surfaceFilmModels/submodels/thermo/phaseChangeModel/waxSolventEvaporation/waxSolventEvaporation.C
index 6a6e342a12..13ab7a4d15 100644
--- a/src/regionModels/surfaceFilmModels/submodels/thermo/phaseChangeModel/waxSolventEvaporation/waxSolventEvaporation.C
+++ b/src/regionModels/surfaceFilmModels/submodels/thermo/phaseChangeModel/waxSolventEvaporation/waxSolventEvaporation.C
@@ -90,7 +90,7 @@ waxSolventEvaporation::waxSolventEvaporation
         (
             typeName + ":Wwax",
             film.regionMesh().time().constant(),
-            film.regionMesh()
+            film.regionMesh().thisDb()
         ),
         coeffDict_.get<scalar>("Wwax")
     ),
@@ -100,7 +100,7 @@ waxSolventEvaporation::waxSolventEvaporation
         (
             typeName + ":Wsolvent",
             film.regionMesh().time().constant(),
-            film.regionMesh()
+            film.regionMesh().thisDb()
         ),
         coeffDict_.get<scalar>("Wsolvent")
     ),
@@ -110,7 +110,7 @@ waxSolventEvaporation::waxSolventEvaporation
         (
             typeName + ":Ysolvent0",
             film.regionMesh().time().constant(),
-            film.regionMesh(),
+            film.regionMesh().thisDb(),
             IOobject::MUST_READ,
             IOobject::NO_WRITE
         )
@@ -121,7 +121,7 @@ waxSolventEvaporation::waxSolventEvaporation
         (
             typeName + ":Ysolvent",
             film.regionMesh().time().timeName(),
-            film.regionMesh(),
+            film.regionMesh().thisDb(),
             IOobject::MUST_READ,
             IOobject::AUTO_WRITE
         ),
@@ -193,7 +193,7 @@ void waxSolventEvaporation::correctModel
         (
             typeName + ":evapRateCoeff",
             film.regionMesh().time().timeName(),
-            film.regionMesh(),
+            film.regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE,
             IOobject::NO_REGISTER
@@ -208,7 +208,7 @@ void waxSolventEvaporation::correctModel
         (
             typeName + ":evapRateInf",
             film.regionMesh().time().timeName(),
-            film.regionMesh(),
+            film.regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE,
             IOobject::NO_REGISTER
diff --git a/src/regionModels/surfaceFilmModels/thermoSingleLayer/thermoSingleLayer.C b/src/regionModels/surfaceFilmModels/thermoSingleLayer/thermoSingleLayer.C
index 30b5653e5f..9202742a83 100644
--- a/src/regionModels/surfaceFilmModels/thermoSingleLayer/thermoSingleLayer.C
+++ b/src/regionModels/surfaceFilmModels/thermoSingleLayer/thermoSingleLayer.C
@@ -324,8 +324,8 @@ thermoSingleLayer::thermoSingleLayer
         IOobject
         (
             "Cp",
-            time().timeName(),
-            regionMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::AUTO_WRITE
         ),
@@ -338,8 +338,8 @@ thermoSingleLayer::thermoSingleLayer
         IOobject
         (
             "kappa",
-            time().timeName(),
-            regionMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::AUTO_WRITE
         ),
@@ -353,8 +353,8 @@ thermoSingleLayer::thermoSingleLayer
         IOobject
         (
             "Tf",
-            time().timeName(),
-            regionMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::MUST_READ,
             IOobject::AUTO_WRITE
         ),
@@ -365,8 +365,8 @@ thermoSingleLayer::thermoSingleLayer
         IOobject
         (
             "Tsf",
-            time().timeName(),
-            regionMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -378,8 +378,8 @@ thermoSingleLayer::thermoSingleLayer
         IOobject
         (
             "Twf",
-            time().timeName(),
-            regionMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -391,8 +391,8 @@ thermoSingleLayer::thermoSingleLayer
         IOobject
         (
             "hf",
-            time().timeName(),
-            regionMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -406,8 +406,8 @@ thermoSingleLayer::thermoSingleLayer
         IOobject
         (
             "primaryEnergyTrans",
-            time().timeName(),
-            regionMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -426,8 +426,8 @@ thermoSingleLayer::thermoSingleLayer
         IOobject
         (
             "hsSp",
-            time().timeName(),
-            regionMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -441,8 +441,8 @@ thermoSingleLayer::thermoSingleLayer
         IOobject
         (
             hsSp_.name(), // Must have same name as hSp_ to enable mapping
-            time().timeName(),
-            primaryMesh(),
+            primaryMesh().time().timeName(),
+            primaryMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -455,8 +455,8 @@ thermoSingleLayer::thermoSingleLayer
         IOobject
         (
             "T", // Same name as T on primary region to enable mapping
-            time().timeName(),
-            regionMesh(),
+            regionMesh().time().timeName(),
+            regionMesh().thisDb(),
             IOobject::NO_READ,
             IOobject::NO_WRITE
         ),
@@ -510,8 +510,8 @@ thermoSingleLayer::thermoSingleLayer
                     IOobject
                     (
                         thermo_.carrier().species()[i],
-                        time().timeName(),
-                        regionMesh(),
+                        regionMesh().time().timeName(),
+                        regionMesh().thisDb(),
                         IOobject::NO_READ,
                         IOobject::NO_WRITE
                     ),
@@ -547,8 +547,8 @@ thermoSingleLayer::thermoSingleLayer
             IOobject
             (
                 "phi",
-                time().timeName(),
-                regionMesh(),
+                regionMesh().time().timeName(),
+                regionMesh().thisDb(),
                 IOobject::READ_IF_PRESENT,
                 IOobject::NO_WRITE,
                 IOobject::NO_REGISTER
diff --git a/src/regionModels/surfaceFilmModels/thermoSingleLayer/thermoSingleLayerI.H b/src/regionModels/surfaceFilmModels/thermoSingleLayer/thermoSingleLayerI.H
index 2cfefdc521..e53bd1a16b 100644
--- a/src/regionModels/surfaceFilmModels/thermoSingleLayer/thermoSingleLayerI.H
+++ b/src/regionModels/surfaceFilmModels/thermoSingleLayer/thermoSingleLayerI.H
@@ -71,8 +71,8 @@ inline tmp<volScalarField> thermoSingleLayer::hs
             IOobject
             (
                 "hs(" + T.name() + ")",
-                time().timeName(),
-                regionMesh(),
+                regionMesh().time().timeName(),
+                regionMesh().thisDb(),
                 IOobject::NO_READ,
                 IOobject::NO_WRITE
             ),
@@ -94,8 +94,8 @@ inline tmp<volScalarField> thermoSingleLayer::T
             IOobject
             (
                 "T(" + hs.name() + ")",
-                time().timeName(),
-                regionMesh(),
+                regionMesh().time().timeName(),
+                regionMesh().thisDb(),
                 IOobject::NO_READ,
                 IOobject::NO_WRITE
             ),
diff --git a/src/regionModels/thermalBaffleModels/thermalBaffle/thermalBaffle.C b/src/regionModels/thermalBaffleModels/thermalBaffle/thermalBaffle.C
index 777b3fced8..75aa061458 100644
--- a/src/regionModels/thermalBaffleModels/thermalBaffle/thermalBaffle.C
+++ b/src/regionModels/thermalBaffleModels/thermalBaffle/thermalBaffle.C
@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2016 OpenFOAM Foundation
-    Copyright (C) 2020 OpenCFD Ltd.
+    Copyright (C) 2020-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -80,7 +80,7 @@ void thermalBaffle::solveEnergy()
             (
                 "tQ",
                 regionMesh().time().timeName(),
-                regionMesh(),
+                regionMesh().thisDb(),
                 IOobject::NO_READ,
                 IOobject::NO_WRITE,
                 IOobject::NO_REGISTER
@@ -172,7 +172,7 @@ thermalBaffle::thermalBaffle
         (
             "qs",
             regionMesh().time().timeName(),
-            regionMesh(),
+            regionMesh().thisDb(),
             IOobject::READ_IF_PRESENT,
             IOobject::NO_WRITE
         ),
@@ -185,7 +185,7 @@ thermalBaffle::thermalBaffle
         (
             "Q",
             regionMesh().time().timeName(),
-            regionMesh(),
+            regionMesh().thisDb(),
             IOobject::READ_IF_PRESENT,
             IOobject::AUTO_WRITE
         ),
@@ -222,7 +222,7 @@ thermalBaffle::thermalBaffle
         (
             "qs",
             regionMesh().time().timeName(),
-            regionMesh(),
+            regionMesh().thisDb(),
             IOobject::READ_IF_PRESENT,
             IOobject::NO_WRITE
         ),
@@ -235,7 +235,7 @@ thermalBaffle::thermalBaffle
         (
             "Q",
             regionMesh().time().timeName(),
-            regionMesh(),
+            regionMesh().thisDb(),
             IOobject::READ_IF_PRESENT,
             IOobject::NO_WRITE
         ),