diff --git a/src/functionObjects/field/Make/files b/src/functionObjects/field/Make/files
index b666221d3a19da28cf988983b2b3c87b795cb27e..1afdfb2ea7d2daafd0526756deb8c98eddab3761 100644
--- a/src/functionObjects/field/Make/files
+++ b/src/functionObjects/field/Make/files
@@ -3,6 +3,7 @@ fieldAverage/fieldAverageItem/fieldAverageItem.C
fieldAverage/fieldAverageItem/fieldAverageItemIO.C
fieldCoordinateSystemTransform/fieldCoordinateSystemTransform.C
+fieldExtents/fieldExtents.C
fieldMinMax/fieldMinMax.C
fieldValues/fieldValue/fieldValue.C
diff --git a/src/functionObjects/field/fieldExtents/fieldExtents.C b/src/functionObjects/field/fieldExtents/fieldExtents.C
new file mode 100644
index 0000000000000000000000000000000000000000..8e65a802eb0af636e48bd92efa81ce5e211d5a22
--- /dev/null
+++ b/src/functionObjects/field/fieldExtents/fieldExtents.C
@@ -0,0 +1,201 @@
+/*---------------------------------------------------------------------------*\
+ ========= |
+ \\ / F ield | OpenFOAM: The Open Source CFD Toolbox
+ \\ / O peration |
+ \\ / A nd | Copyright (C) 2018 OpenCFD Ltd.
+ \\/ M anipulation |
+-------------------------------------------------------------------------------
+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 "fieldExtents.H"
+#include "addToRunTimeSelectionTable.H"
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+namespace Foam
+{
+namespace functionObjects
+{
+ defineTypeNameAndDebug(fieldExtents, 0);
+ addToRunTimeSelectionTable(functionObject, fieldExtents, dictionary);
+}
+}
+
+
+// * * * * * * * * * * * * Protected Member Functions * * * * * * * * * * * //
+
+void Foam::functionObjects::fieldExtents::writeFileHeader(Ostream& os)
+{
+ if (!fieldSet_.updateSelection())
+ {
+ return;
+ }
+
+ if (writtenHeader_)
+ {
+ writeBreak(os);
+ }
+ else
+ {
+ writeHeader(os, "Field extents");
+ writeHeaderValue(os, "Reference position", C0_);
+ writeHeaderValue(os, "Threshold", threshold_);
+ }
+
+ writeCommented(os, "Time");
+
+ forAllConstIters(fieldSet_.selection(), iter)
+ {
+ const word& fieldName = iter();
+ if (internalField_)
+ {
+ writeTabbed(os, fieldName + "_internal");
+ }
+ for (const label patchi : patchIDs_)
+ {
+ const word& patchName = mesh_.boundaryMesh()[patchi].name();
+ writeTabbed(os, fieldName + "_" + patchName);
+ }
+ }
+
+ os << endl;
+
+ writtenHeader_ = true;
+}
+
+
+template<>
+Foam::tmp<Foam::volScalarField> Foam::functionObjects::fieldExtents::calcMask
+(
+ const GeometricField<scalar, fvPatchField, volMesh>& field
+) const
+{
+ return
+ pos
+ (
+ field
+ - dimensionedScalar("t", field.dimensions(), threshold_)
+ );
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors * * * * * * * * * * * * * * //
+
+Foam::functionObjects::fieldExtents::fieldExtents
+(
+ const word& name,
+ const Time& runTime,
+ const dictionary& dict
+)
+:
+ fvMeshFunctionObject(name, runTime, dict),
+ writeFile(mesh_, name, typeName, dict),
+ internalField_(true),
+ threshold_(0),
+ C0_(Zero),
+ fieldSet_(mesh_),
+ patchIDs_()
+{
+ read(dict);
+
+ // Note: delay creating the output file header to handle field names
+ // specified using regular expressions
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions * * * * * * * * * * * * * //
+
+bool Foam::functionObjects::fieldExtents::read(const dictionary& dict)
+{
+ if (fvMeshFunctionObject::read(dict) && writeFile::read(dict))
+ {
+ threshold_ = dict.get<scalar>("threshold");
+
+ dict.readIfPresent<bool>("internalField", internalField_);
+
+ dict.readIfPresent<vector>("referencePosition", C0_);
+
+ patchIDs_.clear();
+ const polyBoundaryMesh& pbm = mesh_.boundaryMesh();
+
+ wordReList patchNames;
+ if (dict.readIfPresent("patches", patchNames))
+ {
+ for (const wordRe& name : patchNames)
+ {
+ patchIDs_.insert(pbm.findIndices(name));
+ }
+ }
+ else
+ {
+ // Add all non-processor and non-empty patches
+ forAll(pbm, patchi)
+ {
+ const polyPatch& pp = pbm[patchi];
+ if (!isA<processorPolyPatch>(pp) && !isA<emptyPolyPatch>(pp))
+ {
+ patchIDs_.insert(patchi);
+ }
+ }
+ }
+
+ if (!internalField_ && patchIDs_.empty())
+ {
+ IOWarningInFunction(dict)
+ << "No internal field or patches selected - no field extent "
+ << "information will be generated" << endl;
+ }
+
+ fieldSet_.read(dict);
+
+ return true;
+ }
+
+ return false;
+}
+
+
+bool Foam::functionObjects::fieldExtents::execute()
+{
+ return true;
+}
+
+
+bool Foam::functionObjects::fieldExtents::write()
+{
+ writeFileHeader(file());
+
+ Log << type() << " " << name() << " write:" << nl;
+
+ for (const word& fieldName : fieldSet_.selection())
+ {
+ calcFieldExtents<scalar>(fieldName, true);
+ calcFieldExtents<vector>(fieldName);
+ calcFieldExtents<sphericalTensor>(fieldName);
+ calcFieldExtents<symmTensor>(fieldName);
+ calcFieldExtents<tensor>(fieldName);
+ }
+
+ Log << endl;
+
+ return true;
+}
+
+
+// ************************************************************************* //
diff --git a/src/functionObjects/field/fieldExtents/fieldExtents.H b/src/functionObjects/field/fieldExtents/fieldExtents.H
new file mode 100644
index 0000000000000000000000000000000000000000..9d4d8ac93977cdef58c2fcf835ea3d731066ac42
--- /dev/null
+++ b/src/functionObjects/field/fieldExtents/fieldExtents.H
@@ -0,0 +1,207 @@
+/*---------------------------------------------------------------------------*\
+ ========= |
+ \\ / F ield | OpenFOAM: The Open Source CFD Toolbox
+ \\ / O peration |
+ \\ / A nd | Copyright (C) 2018 OpenCFD Ltd.
+ \\/ M anipulation |
+-------------------------------------------------------------------------------
+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::fieldExtents
+
+Group
+ grpFieldFunctionObjects
+
+Description
+ Calculates the spatial minimum and maximum extents of a field
+
+ The extents are derived from the bound box limits after identifying the
+ locations where field values exceed the user-supplied threshold value.
+
+Usage
+ Example of function object specification:
+ \verbatim
+ fieldExtents1
+ {
+ type fieldExtents;
+ libs ("libfieldFunctionObjects.so");
+ ...
+ writeToFile yes;
+ log yes;
+ fields (alpha);
+ threshold 0.5;
+ patches ();
+ }
+ \endverbatim
+
+ Where the entries comprise:
+ \table
+ Property | Description | Required | Default value
+ type | type name: fieldExtents | yes |
+ writeToFile | write extents data to file | no | yes
+ log | write extents data to standard output | no | yes
+ internalField | Process the internal field | no | yes
+ threshold | Field value to identify extents boundary | yes |
+ referencePosition | Reference position | no | (0 0 0)
+ fields | list of fields to process | yes |
+ patches | list of patches to process | no | \<all patches\>
+ \endtable
+
+ Output data is written to the file \<timeDir\>/fieldExtents.dat
+
+Note
+ For non-scalar fields, the magnitude of the field is employed and compared
+ to the threshold value.
+
+See also
+ Foam::functionObjects::fvMeshFunctionObject
+ Foam::functionObjects::writeFile
+
+SourceFiles
+ fieldExtents.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef functionObjects_fieldExtents_H
+#define functionObjects_fieldExtents_H
+
+#include "fvMeshFunctionObject.H"
+#include "writeFile.H"
+#include "volFieldSelection.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+namespace functionObjects
+{
+
+/*---------------------------------------------------------------------------*\
+ Class fieldExtents Declaration
+\*---------------------------------------------------------------------------*/
+
+class fieldExtents
+:
+ public fvMeshFunctionObject,
+ public writeFile
+{
+protected:
+
+ // Protected data
+
+ //- Flag to write the internal field extents
+ bool internalField_;
+
+ //- Threshold value
+ scalar threshold_;
+
+ //- Reference position; default = (0 0 0)
+ point C0_;
+
+ //- Fields to assess
+ volFieldSelection fieldSet_;
+
+ //- Patches to assess
+ labelHashSet patchIDs_;
+
+
+ // Protected Member Functions
+
+ //- Output file header information
+ virtual void writeFileHeader(Ostream& os);
+
+ //- Return the field mask
+ template<class Type>
+ tmp<volScalarField> calcMask
+ (
+ const GeometricField<Type, fvPatchField, volMesh>& field
+ ) const;
+
+ //- Main calculation
+ template<class Type>
+ void calcFieldExtents
+ (
+ const word& fieldName,
+ const bool calcMag = false
+ );
+
+ //- No copy construct
+ fieldExtents(const fieldExtents&) = delete;
+
+ //- No copy assignment
+ void operator=(const fieldExtents&) = delete;
+
+
+public:
+
+ //- Runtime type information
+ TypeName("fieldExtents");
+
+
+ // Constructors
+
+ //- Construct from Time and dictionary
+ fieldExtents
+ (
+ const word& name,
+ const Time& runTime,
+ const dictionary& dict
+ );
+
+
+ //- Destructor
+ virtual ~fieldExtents() = default;
+
+
+ // Member Functions
+
+ //- Read the field extents data
+ virtual bool read(const dictionary&);
+
+ //- Execute, currently does nothing
+ virtual bool execute();
+
+ //- Write the fieldExtents
+ virtual bool write();
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+template<>
+tmp<volScalarField> fieldExtents::calcMask
+(
+ const GeometricField<scalar, fvPatchField, volMesh>& field
+) const;
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace functionObjects
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#ifdef NoRepository
+ #include "fieldExtentsTemplates.C"
+#endif
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //
diff --git a/src/functionObjects/field/fieldExtents/fieldExtentsTemplates.C b/src/functionObjects/field/fieldExtents/fieldExtentsTemplates.C
new file mode 100644
index 0000000000000000000000000000000000000000..9ea87aef7de36c016d7b5f09c770ad8694e466e2
--- /dev/null
+++ b/src/functionObjects/field/fieldExtents/fieldExtentsTemplates.C
@@ -0,0 +1,120 @@
+/*---------------------------------------------------------------------------*\
+ ========= |
+ \\ / F ield | OpenFOAM: The Open Source CFD Toolbox
+ \\ / O peration |
+ \\ / A nd | Copyright (C) 2018 OpenCFD Ltd.
+ \\/ M anipulation |
+-------------------------------------------------------------------------------
+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 "fieldExtents.H"
+#include "volFields.H"
+#include "boundBox.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+template<class Type>
+Foam::tmp<Foam::volScalarField> Foam::functionObjects::fieldExtents::calcMask
+(
+ const GeometricField<Type, fvPatchField, volMesh>& field
+) const
+{
+ return
+ pos
+ (
+ mag(field)
+ - dimensionedScalar("t", field.dimensions(), threshold_)
+ );
+}
+
+
+template<class Type>
+void Foam::functionObjects::fieldExtents::calcFieldExtents
+(
+ const word& fieldName,
+ const bool calcMag
+)
+{
+ typedef GeometricField<Type, fvPatchField, volMesh> VolFieldType;
+
+ const VolFieldType* fieldPtr =
+ obr_.lookupObjectPtr<VolFieldType>(fieldName);
+
+ if (!fieldPtr)
+ {
+ return;
+ }
+
+ auto extents = [this](const scalarField& mask, const vectorField& C)
+ {
+ boundBox extents(boundBox::invertedBox);
+ forAll(mask, i)
+ {
+ if (mask[i] > 0.5)
+ {
+ extents.add(C[i] - C0_);
+ }
+ };
+
+ extents.reduce();
+
+ if (extents.empty())
+ {
+ extents.add(point::zero);
+ }
+
+ return extents;
+ };
+
+ Log << "field: " << fieldName << nl;
+
+ writeTime(file());
+
+ tmp<volScalarField> tmask = calcMask<Type>(*fieldPtr);
+ const volScalarField& mask = tmask();
+
+ // Internal field
+ if (internalField_)
+ {
+ boundBox bb(extents(mask, mesh_.C()));
+ Log << " internal field: " << bb << nl;
+ file() << bb;
+
+ this->setResult(fieldName + "_internal_min" , bb.min());
+ this->setResult(fieldName + "_internal_max", bb.max());
+ }
+
+ // Patches
+ for (const label patchi : patchIDs_)
+ {
+ const fvPatchScalarField& maskp = mask.boundaryField()[patchi];
+ boundBox bb(extents(maskp, maskp.patch().Cf()));
+ const word& patchName = maskp.patch().name();
+ Log << " patch " << patchName << ": " << bb << nl;
+ file() << bb;
+ this->setResult(fieldName + "_" + patchName + "_min", bb.min());
+ this->setResult(fieldName + "_" + patchName + "_max", bb.max());
+ }
+
+ Log << endl;
+ file() << endl;
+}
+
+
+// ************************************************************************* //
diff --git a/tutorials/lagrangian/reactingParcelFoam/rivuletPanel/system/controlDict b/tutorials/lagrangian/reactingParcelFoam/rivuletPanel/system/controlDict
index b628460e8ed45dadeae7dbb93974ffd0422e308b..363963055dcc0b3d80237a20c8ac7e3313a63a20 100644
--- a/tutorials/lagrangian/reactingParcelFoam/rivuletPanel/system/controlDict
+++ b/tutorials/lagrangian/reactingParcelFoam/rivuletPanel/system/controlDict
@@ -51,5 +51,18 @@ maxCo 0.3;
maxDeltaT 1e-03;
+functions
+{
+ fieldExtents
+ {
+ type fieldExtents;
+ libs ("libfieldFunctionObjects.so");
+ region wallFilmRegion;
+ threshold 0.5;
+ fields (alpha);
+ internalField yes;
+ patches ();
+ }
+}
// ************************************************************************* //