fvOptions::limitVelocity: New fvOption to limit the maximum velocity magnitude

e.g. to avoid excessive unphysical velocities generated during slamming events in
incompressible VoF simulations

Usage
    Example usage:
    limitU
    {
        type            limitVelocity;
        active          yes;

        limitVelocityCoeffs
        {
            selectionMode   all;
            max             100;
        }
    }

src/fvOptions/Make/files

@@ -56,6 +56,7 @@ constraints/fixedTemperatureConstraint/fixedTemperatureConstraint.C
 /* Corrections */
 
 corrections/limitTemperature/limitTemperature.C
+corrections/limitVelocity/limitVelocity.C
 
 
 LIB = $(FOAM_LIBBIN)/libfvOptions

src/fvOptions/corrections/limitVelocity/limitVelocity.C

+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2016 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/>.
+
+\*---------------------------------------------------------------------------*/
+
+#include "limitVelocity.H"
+#include "volFields.H"
+#include "addToRunTimeSelectionTable.H"
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+namespace Foam
+{
+namespace fv
+{
+    defineTypeNameAndDebug(limitVelocity, 0);
+    addToRunTimeSelectionTable
+    (
+        option,
+        limitVelocity,
+        dictionary
+    );
+}
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::fv::limitVelocity::limitVelocity
+(
+    const word& name,
+    const word& modelType,
+    const dictionary& dict,
+    const fvMesh& mesh
+)
+:
+    cellSetOption(name, modelType, dict, mesh),
+    UName_(coeffs_.lookupOrDefault<word>("U", "U")),
+    max_(readScalar(coeffs_.lookup("max")))
+{
+    fieldNames_.setSize(1, UName_);
+    applied_.setSize(1, false);
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+bool Foam::fv::limitVelocity::read(const dictionary& dict)
+{
+    if (cellSetOption::read(dict))
+    {
+        coeffs_.lookup("max") >> max_;
+
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+
+void Foam::fv::limitVelocity::correct(volVectorField& U)
+{
+    const scalar maxSqrU = sqr(max_);
+
+    vectorField& Uif = U.primitiveFieldRef();
+
+    forAll(cells_, i)
+    {
+        const label celli = cells_[i];
+
+        const scalar magSqrUi = magSqr(Uif[celli]);
+
+        if (magSqrUi > maxSqrU)
+        {
+            Uif[celli] *= maxSqrU/magSqrUi;
+        }
+    }
+
+    // handle boundaries in the case of 'all'
+    if (selectionMode_ == smAll)
+    {
+        volVectorField::Boundary& Ubf = U.boundaryFieldRef();
+
+        forAll(Ubf, patchi)
+        {
+            fvPatchVectorField& Up = Ubf[patchi];
+
+            if (!Up.fixesValue())
+            {
+                forAll(Up, facei)
+                {
+                    const scalar magSqrUi = magSqr(Up[facei]);
+
+                    if (magSqrUi > maxSqrU)
+                    {
+                        Up[facei] *= maxSqrU/magSqrUi;
+                    }
+                }
+            }
+        }
+    }
+}
+
+
+// ************************************************************************* //

src/fvOptions/corrections/limitVelocity/limitVelocity.H

+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Copyright (C) 2016 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::fv::limitVelocity
+
+Description
+    Limits the maximum velocity magnitude to the specified \c max value.
+
+Usage
+    Example usage:
+    \verbatim
+    limitU
+    {
+        type            limitVelocity;
+        active          yes;
+
+        limitVelocityCoeffs
+        {
+            selectionMode   all;
+            max             100;
+        }
+    }
+    \endverbatim
+
+SourceFiles
+    limitVelocity.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef limitVelocity_H
+#define limitVelocity_H
+
+#include "cellSetOption.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+namespace fv
+{
+
+/*---------------------------------------------------------------------------*\
+                 Class limitVelocity Declaration
+\*---------------------------------------------------------------------------*/
+
+class limitVelocity
+:
+    public cellSetOption
+{
+
+protected:
+
+    // Protected data
+
+        //- Velocity field name, default = U
+        word UName_;
+
+        //- Maximum velocity magnitude
+        scalar max_;
+
+
+private:
+
+    // Private Member Functions
+
+        //- Disallow default bitwise copy construct
+        limitVelocity(const limitVelocity&);
+
+        //- Disallow default bitwise assignment
+        void operator=(const limitVelocity&);
+
+
+public:
+
+    //- Runtime type information
+    TypeName("limitVelocity");
+
+
+    // Constructors
+
+        //- Construct from components
+        limitVelocity
+        (
+            const word& name,
+            const word& modelType,
+            const dictionary& dict,
+            const fvMesh& mesh
+        );
+
+
+    //- Destructor
+    virtual ~limitVelocity()
+    {}
+
+
+    // Member Functions
+
+        //- Read dictionary
+        virtual bool read(const dictionary& dict);
+
+        //- Correct the energy field
+        virtual void correct(volVectorField& U);
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace fv
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //