ENH: new continuityError function object

Example usage:

    continuityError1
    {
        type        continuityError;
        libs        ("libfieldFunctionObjects.so");
        ...
        writeToFile yes;
        log         yes;
        phi         phi;
    }

src/functionObjects/field/continuityError/continuityError.C

@@ -0,0 +1,144 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2019 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 "continuityError.H"
+#include "volFields.H"
+#include "fvcDiv.H"
+#include "addToRunTimeSelectionTable.H"
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+namespace Foam
+{
+namespace functionObjects
+{
+    defineTypeNameAndDebug(continuityError, 0);
+    addToRunTimeSelectionTable(functionObject, continuityError, dictionary);
+}
+}
+
+
+// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
+
+void Foam::functionObjects::continuityError::writeFileHeader(Ostream& os)
+{
+    writeHeader(os, "Continuity error");
+
+    writeCommented(os, "Time");
+    writeCommented(os, "Local");
+    writeCommented(os, "Global");
+    writeCommented(os, "Cumulative");
+
+    os  << endl;
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::functionObjects::continuityError::continuityError
+(
+    const word& name,
+    const Time& runTime,
+    const dictionary& dict
+)
+:
+    fvMeshFunctionObject(name, runTime, dict),
+    writeFile(mesh_, name, typeName, dict),
+    phiName_("phi"),
+    cumulative_(getProperty<scalar>("cumulative"))
+{
+    if (read(dict))
+    {
+        writeFileHeader(file());
+    }
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+bool Foam::functionObjects::continuityError::read(const dictionary& dict)
+{
+    if (fvMeshFunctionObject::read(dict) && writeFile::read(dict))
+    {
+        dict.readIfPresent("phi", phiName_);
+
+        return true;
+    }
+
+    return false;
+}
+
+
+bool Foam::functionObjects::continuityError::execute()
+{
+    return true;
+}
+
+
+bool Foam::functionObjects::continuityError::write()
+{
+    const auto phiPtr = mesh_.lookupObjectPtr<surfaceScalarField>(phiName_);
+
+    if (!phiPtr)
+    {
+        WarningInFunction
+            << "Unable to find flux field " << phiName_
+            << endl;
+
+        return false;
+    }
+
+    const volScalarField error(fvc::div(*phiPtr));
+    const scalar deltaT = mesh_.time().deltaTValue();
+
+    scalar local = deltaT*mag(error)().weightedAverage(mesh_.V()).value();
+    scalar global = deltaT*error.weightedAverage(mesh_.V()).value();
+    cumulative_ += global;
+
+    Ostream& os = file();
+
+    writeTime(os);
+
+    os  << local << tab
+        << global << tab
+        << cumulative_ << endl;
+
+    Log << type() << " " << name() <<  " write:" << nl
+        << "    local = " << local << nl
+        << "    global = " << global << nl
+        << "    cumulative = " << cumulative_ << nl
+        << endl;
+
+    setResult("local", local);
+    setResult("global", global);
+    setResult("cumulative", cumulative_);
+
+    setProperty<scalar>("cumulative", cumulative_);
+
+    return true;
+}
+
+
+// ************************************************************************* //