functionObjects::cylindricalFunctionObject: New functionObject to transform velocity into cylindrical polar coordinates

Description
    Transforms the specified velocity field into a
    cylindrical polar coordinate system or back to Cartesian.

    Example of function object specification to convert the velocity field U
    into cylindrical polar coordinates before averaging and returning the
    average to Cartesian coordinates:
    \verbatim
    cartesianToCylindrical
    {
        type        cylindrical;
        libs        ("libfieldFunctionObjects.so");

        origin      (0 0 0);
        axis        (0 0 1);

        field       U;

        writeControl    outputTime;
        writeInterval   1;
    }

    #includeFunc fieldAverage(cylindrical(U))

    cylindricalToCartesian
    {
        type        cylindrical;
        libs        ("libfieldFunctionObjects.so");

        origin      (0 0 0);
        axis        (0 0 1);

        field       cylindrical(U)Mean;
        toCartesian true;
        result      UMean;

        writeControl    outputTime;
        writeInterval   1;
    }
    \endverbatim
    This is particularly useful for cases with rotating regions, e.g. mixer
    vessels with AMI.

See tutorials/incompressible/pimpleFoam/laminar/mixerVesselAMI2D

src/functionObjects/field/cylindrical/cylindricalFunctionObject.H

@@ -0,0 +1,150 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     | Website:  https://openfoam.org
+    \\  /    A nd           | Copyright (C) 2020 OpenFOAM Foundation
+     \\/     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::cylindrical
+
+Description
+    Transforms the specified velocity field into a
+    cylindrical polar coordinate system or back to Cartesian.
+
+    Example of function object specification to convert the velocity field U
+    into cylindrical polar coordinates before averaging and returning the
+    average to Cartesian coordinates:
+    \verbatim
+    cartesianToCylindrical
+    {
+        type        cylindrical;
+        libs        ("libfieldFunctionObjects.so");
+
+        origin      (0 0 0);
+        axis        (0 0 1);
+
+        field       U;
+
+        writeControl    outputTime;
+        writeInterval   1;
+    }
+
+    #includeFunc fieldAverage(cylindrical(U))
+
+    cylindricalToCartesian
+    {
+        type        cylindrical;
+        libs        ("libfieldFunctionObjects.so");
+
+        origin      (0 0 0);
+        axis        (0 0 1);
+
+        field       cylindrical(U)Mean;
+        toCartesian true;
+        result      UMean;
+
+        writeControl    outputTime;
+        writeInterval   1;
+    }
+    \endverbatim
+    This is particularly useful for cases with rotating regions, e.g. mixer
+    vessels with AMI.
+
+See also
+    Foam::functionObjects::fieldExpression
+    Foam::functionObjects::fvMeshFunctionObject
+
+SourceFiles
+    cylindrical.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef cylindricalFunctionObject_H
+#define cylindricalFunctionObject_H
+
+#include "fieldExpression.H"
+#include "primitiveFieldsFwd.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+namespace functionObjects
+{
+
+/*---------------------------------------------------------------------------*\
+                          Class cylindrical Declaration
+\*---------------------------------------------------------------------------*/
+
+class cylindrical
+:
+    public fieldExpression
+{
+    // Private Data
+
+        vector origin_;
+
+        vector axis_;
+
+
+    // Private Member Functions
+
+        tensor R(const vector& p) const;
+
+        void transform(vectorField& vf, const vectorField& points) const;
+
+        bool toCartesian_;
+
+        //- Calculate the cylindrical field and return true if successful
+        virtual bool calc();
+
+
+public:
+
+    //- Runtime type information
+    TypeName("cylindrical");
+
+
+    // Constructors
+
+        //- Construct from Time and dictionary
+        cylindrical
+        (
+            const word& name,
+            const Time& runTime,
+            const dictionary& dict
+        );
+
+
+    //- Destructor
+    virtual ~cylindrical();
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace functionObjects
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //