diff --git a/src/regionFaModels/Make/files b/src/regionFaModels/Make/files
index cd0717dbd83b2fc4ffd6e125939af84db33f3251..375a0c49d386c1d214c7ba7a06b6e03acb005c41 100644
--- a/src/regionFaModels/Make/files
+++ b/src/regionFaModels/Make/files
@@ -42,5 +42,6 @@ liquidFilm/kinematicThinFilm/kinematicThinFilm.C
derivedFvPatchFields/filmShell/velocityFilmShellFvPatchVectorField.C
functionObjects/setTimeStep/setTimeStepFaRegionsFunctionObject.C
+functionObjects/surfaceCourantNumber/surfaceCourantNumber.C
LIB = $(FOAM_LIBBIN)/libregionFaModels
diff --git a/src/regionFaModels/functionObjects/surfaceCourantNumber/surfaceCourantNumber.C b/src/regionFaModels/functionObjects/surfaceCourantNumber/surfaceCourantNumber.C
new file mode 100644
index 0000000000000000000000000000000000000000..49c7dc76c485b5b79409755a88af6d688856595f
--- /dev/null
+++ b/src/regionFaModels/functionObjects/surfaceCourantNumber/surfaceCourantNumber.C
@@ -0,0 +1,227 @@
+/*---------------------------------------------------------------------------*\
+ ========= |
+ \\ / F ield | OpenFOAM: The Open Source CFD Toolbox
+ \\ / O peration |
+ \\ / A nd | www.openfoam.com
+ \\/ M anipulation |
+-------------------------------------------------------------------------------
+ Copyright (C) 2024 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 "surfaceCourantNumber.H"
+#include "fvMesh.H"
+#include "faMesh.H"
+#include "areaFields.H"
+#include "edgeFields.H"
+#include "facEdgeIntegrate.H"
+#include "zeroGradientFaPatchFields.H"
+#include "addToRunTimeSelectionTable.H"
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+namespace Foam
+{
+namespace functionObjects
+{
+ defineTypeNameAndDebug(surfaceCourantNumber, 0);
+ addToRunTimeSelectionTable(functionObject, surfaceCourantNumber, dictionary);
+}
+}
+
+
+// * * * * * * * * * * * * * Private Member Functions * * * * * * * * * * * //
+
+void Foam::functionObjects::surfaceCourantNumber::writeFileHeader(Ostream& os)
+{
+ writeHeader(os, "Surface Courant Number");
+
+ writeCommented(os, "Time");
+ writeTabbed(os, "min");
+ writeTabbed(os, "max");
+ writeTabbed(os, "mean");
+ os << endl;
+
+ writtenHeader_ = true;
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors * * * * * * * * * * * * * * //
+
+Foam::functionObjects::surfaceCourantNumber::surfaceCourantNumber
+(
+ const word& name,
+ const Time& runTime,
+ const dictionary& dict
+)
+:
+ fvMeshFunctionObject(name, runTime, dict),
+ writeFile(mesh_, name, typeName, dict),
+ resultName_("surfaceCo"),
+ phisName_("phis"),
+ rhoName_("rho")
+{
+ read(dict);
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions * * * * * * * * * * * * * //
+
+bool Foam::functionObjects::surfaceCourantNumber::read(const dictionary& dict)
+{
+ if (!fvMeshFunctionObject::read(dict) || !writeFile::read(dict))
+ {
+ return false;
+ }
+
+ dict.readIfPresent("result", resultName_);
+ dict.readIfPresent("phis", phisName_);
+ dict.readIfPresent("rho", rhoName_);
+
+ // Registry containing all finite-area meshes on the polyMesh
+ const auto* faRegistryPtr = faMesh::registry(mesh_);
+
+ if (!faRegistryPtr)
+ {
+ FatalIOErrorInFunction(dict)
+ << "No finite-area object registry is available."
+ << abort(FatalIOError);
+ }
+
+ word areaName;
+
+ if (!dict.readIfPresent("area", areaName))
+ {
+ wordList available = faRegistryPtr->sortedNames<faMesh>();
+ if (!available.empty())
+ {
+ areaName = available.front();
+ }
+ }
+
+ if (areaName.empty())
+ {
+ FatalIOErrorInFunction(dict)
+ << "No name for finite-area mesh is available."
+ << abort(FatalIOError);
+ }
+
+ faMeshPtr_ = std::shared_ptr<const faMesh>
+ (
+ faRegistryPtr->cfindObject<faMesh>(areaName),
+ [](const faMesh*) { /* no-op deleter to avoid double deletion */ }
+ );
+
+ return true;
+}
+
+
+bool Foam::functionObjects::surfaceCourantNumber::execute()
+{
+ if (!faMeshPtr_->foundObject<edgeScalarField>(phisName_))
+ {
+ WarningInFunction
+ << "No edge flux field is available. "
+ << "Name of provided edge flux field (phi): " << phisName_
+ << endl;
+
+ return false;
+ }
+
+ const auto& phis = faMeshPtr_->lookupObject<edgeScalarField>(phisName_);
+
+ tmp<areaScalarField::Internal> tCo =
+ (0.5*faMeshPtr_->time().deltaT())
+ *fac::edgeSum(mag(phis))()()
+ /faMeshPtr_->S();
+
+ areaScalarField::Internal Co = tCo.ref();
+
+ if (Co.dimensions() == dimDensity)
+ {
+ Co /= faMeshPtr_->lookupObject<areaScalarField>(rhoName_);
+ }
+
+ auto* resultPtr = faMeshPtr_->getObjectPtr<areaScalarField>(resultName_);
+
+ if (!resultPtr)
+ {
+ resultPtr = new areaScalarField
+ (
+ IOobject
+ (
+ resultName_,
+ faMeshPtr_->time().timeName(),
+ *faMeshPtr_,
+ IOobjectOption()
+ ),
+ *faMeshPtr_,
+ dimensionedScalar(dimless, Zero),
+ faPatchFieldBase::zeroGradientType()
+ );
+ regIOobject::store(resultPtr);
+ }
+ auto& result = *resultPtr;
+
+ result.internalFieldRef() = tCo;
+ result.correctBoundaryConditions();
+
+
+ const scalarMinMax limits(gMinMax(result));
+ const scalar mean = gAverage(result);
+
+ Log << "Surface Courant number: "
+ << "mean: " << mean
+ << " max: " << limits.max()
+ << endl;
+
+ if (writeToFile())
+ {
+ if (!writtenHeader_) writeFileHeader(file());
+
+ writeCurrentTime(file());
+ file()
+ << token::TAB << limits.min()
+ << token::TAB << limits.max()
+ << token::TAB << mean
+ << endl;
+ }
+
+ return true;
+}
+
+
+bool Foam::functionObjects::surfaceCourantNumber::write()
+{
+ const auto* result = faMeshPtr_->cfindObject<areaScalarField>(resultName_);
+
+ if (!result)
+ {
+ return false;
+ }
+
+ Log << type() << " " << name() << " write: " << result->name() << endl;
+
+ result->write();
+
+ return true;
+}
+
+
+// ************************************************************************* //
diff --git a/src/regionFaModels/functionObjects/surfaceCourantNumber/surfaceCourantNumber.H b/src/regionFaModels/functionObjects/surfaceCourantNumber/surfaceCourantNumber.H
new file mode 100644
index 0000000000000000000000000000000000000000..8c64a01b627b1684ecb21fb6a55b65705d14b1c5
--- /dev/null
+++ b/src/regionFaModels/functionObjects/surfaceCourantNumber/surfaceCourantNumber.H
@@ -0,0 +1,175 @@
+/*---------------------------------------------------------------------------*\
+ ========= |
+ \\ / F ield | OpenFOAM: The Open Source CFD Toolbox
+ \\ / O peration |
+ \\ / A nd | www.openfoam.com
+ \\/ M anipulation |
+-------------------------------------------------------------------------------
+ Copyright (C) 2024 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/>.
+
+Class
+ Foam::functionObjects::surfaceCourantNumber
+
+Description
+ Computes the surface Courant number field at finite-area face centres.
+
+ Operands:
+ \table
+ Operand | Type | Location
+ input | - | -
+ output file | dat <!--
+ --> | postProcessing/\<FO\>/\<time\>/\<file\>
+ output field | areaScalarField | \<time\>/\<outField\>
+ \endtable
+
+Usage
+ Minimal example by using \c system/controlDict.functions:
+ \verbatim
+ surfaceCourantNumber1
+ {
+ // Mandatory entries
+ type surfaceCourantNumber;
+ libs (regionFaModels);
+
+ // Optional entries
+ area <word>;
+ result <word>;
+ phis <word>;
+ rho <word>;
+
+ // Inherited entries
+ ...
+ }
+ \endverbatim
+
+ where the entries mean:
+ \table
+ Property | Description | Type | Reqd | Deflt
+ type | Type name: surfaceCourantNumber | word | yes | -
+ libs | Library name: regionFaModels | word | yes | -
+ area | Name of finite-area region | word | no | region0
+ result | Name of result field | word | no | surfaceCo
+ phis | Name of edge flux field | word | no | phis
+ rho | Name of density field | word | no | rho
+ \endtable
+
+ The inherited entries are elaborated in:
+ - \link fvMeshFunctionObject.H \endlink
+ - \link writeFile.H \endlink
+
+Note
+ - The \c surfaceCourantNumber calculates the Courant number at face centers,
+ rather than at edge centers.
+
+SourceFiles
+ surfaceCourantNumber.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef functionObjects_surfaceCourantNumber_H
+#define functionObjects_surfaceCourantNumber_H
+
+#include "fvMeshFunctionObject.H"
+#include "writeFile.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+// Forward Declarations
+class faMesh;
+
+namespace functionObjects
+{
+
+/*---------------------------------------------------------------------------*\
+ Class surfaceCourantNumber Declaration
+\*---------------------------------------------------------------------------*/
+
+class surfaceCourantNumber
+:
+ public fvMeshFunctionObject,
+ public writeFile
+{
+ // Private Data
+
+ //- Name of result field
+ word resultName_;
+
+ //- Name of edge flux field
+ word phisName_;
+
+ //- Name of density field
+ word rhoName_;
+
+ //- Reference to finite-area object registry
+ std::shared_ptr<const faMesh> faMeshPtr_;
+
+
+ // Private Member Functions
+
+ //- Output file header information
+ virtual void writeFileHeader(Ostream& os);
+
+
+public:
+
+ //- Runtime type information
+ TypeName("surfaceCourantNumber");
+
+
+ // Constructors
+
+ //- Construct from Time and dictionary
+ surfaceCourantNumber
+ (
+ const word& name,
+ const Time& runTime,
+ const dictionary& dict
+ );
+
+
+ //- Destructor
+ virtual ~surfaceCourantNumber() = default;
+
+
+ // Member Functions
+
+ //- Read the surfaceCourantNumber data
+ virtual bool read(const dictionary&);
+
+ //- Calculate the Courant number field and return true if successful
+ virtual bool execute();
+
+ //- Write the result field
+ virtual bool write();
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace functionObjects
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //
diff --git a/tutorials/finiteArea/liquidFilmFoam/cylinder/system/FOsurfaceCourantNumber b/tutorials/finiteArea/liquidFilmFoam/cylinder/system/FOsurfaceCourantNumber
new file mode 100644
index 0000000000000000000000000000000000000000..aa255d634cc555748fdf0a7abf4ad7515470176b
--- /dev/null
+++ b/tutorials/finiteArea/liquidFilmFoam/cylinder/system/FOsurfaceCourantNumber
@@ -0,0 +1,38 @@
+/*--------------------------------*- C++ -*----------------------------------*\
+| ========= | |
+| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
+| \\ / O peration | Version: v2406 |
+| \\ / A nd | Website: www.openfoam.com |
+| \\/ M anipulation | |
+\*---------------------------------------------------------------------------*/
+
+surfaceCourantNumber1
+{
+ // Mandatory entries
+ type surfaceCourantNumber;
+ libs (regionFaModels);
+
+ // Optional entries
+ area region0;
+ result surfaceCourantNumberField;
+ rho rho;
+ phis phis;
+
+ // Inherited entries
+ writePrecision 6;
+ writeToFile true;
+ useUserTime true;
+
+ region region0;
+ enabled true;
+ log true;
+ timeStart 0;
+ timeEnd 1000;
+ executeControl timeStep;
+ executeInterval 1;
+ writeControl writeTime;
+ writeInterval -1;
+}
+
+
+// ************************************************************************* //
diff --git a/tutorials/finiteArea/liquidFilmFoam/cylinder/system/controlDict b/tutorials/finiteArea/liquidFilmFoam/cylinder/system/controlDict
index 70074e2c4af941e8eab61c7aad5dcad49090fea4..02c1b5c8b59d5852b32512b6e49cb2d95299a41f 100644
--- a/tutorials/finiteArea/liquidFilmFoam/cylinder/system/controlDict
+++ b/tutorials/finiteArea/liquidFilmFoam/cylinder/system/controlDict
@@ -50,5 +50,9 @@ maxCo 5;
maxDeltaT 0.1;
+functions
+{
+ #include "FOsurfaceCourantNumber"
+}
// ************************************************************************* //