ENH: boundary conditions with expressions

src/finiteVolume/Make/files

@@ -272,6 +272,12 @@ $(volumeExpr)/volumeExprDriverFields.C
 $(volumeExpr)/volumeExprLemonParser.lyy-m4
 $(volumeExpr)/volumeExprScanner.cc
 
+fieldExpr = $(expr)/fields
+$(fieldExpr)/base/patchExprFieldBase.C
+$(fieldExpr)/fvPatchFields/exprFixedValueFvPatchFields.C
+$(fieldExpr)/fvPatchFields/exprMixedFvPatchFields.C
+$(fieldExpr)/pointPatchFields/exprValuePointPatchFields.C
+
 
 fvMatrices/fvMatrices.C
 fvMatrices/fvScalarMatrix/fvScalarMatrix.C

src/finiteVolume/expressions/fields/base/patchExprFieldBase.C

@@ -0,0 +1,186 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Original code Copyright (C) 2011-2018 Bernhard Gschaider
+    Copyright (C) 2019 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 "patchExprFieldBase.H"
+#include "facePointPatch.H"
+#include "fvMesh.H"
+#include "fvPatch.H"
+#include "pointMesh.H"
+
+// * * * * * * * * * * * * * Static Member Functions * * * * * * * * * * * * //
+
+const Foam::fvPatch&
+Foam::expressions::patchExprFieldBase::getFvPatch(const facePointPatch& pp)
+{
+    const polyMesh& pmesh = pp.boundaryMesh().mesh().mesh();
+
+    const fvMesh* meshptr = isA<fvMesh>(pmesh);
+
+    if (!meshptr)
+    {
+        FatalErrorInFunction
+            << "Point patch not attached to a base fvMesh, "
+            << "cannot use patch expressions" << nl << endl
+            << exit(FatalError);
+    }
+
+    return meshptr->boundary()[pp.index()];
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+Foam::expressions::patchExprFieldBase::patchExprFieldBase()
+:
+    patchExprFieldBase(false)
+{}
+
+
+Foam::expressions::patchExprFieldBase::patchExprFieldBase
+(
+    bool allowGradient
+)
+:
+    debug_(false),
+    allowGradient_(allowGradient),
+    evalOnConstruct_(false),
+    valueExpr_(),
+    gradExpr_(),
+    fracExpr_()
+{}
+
+
+Foam::expressions::patchExprFieldBase::patchExprFieldBase
+(
+    const dictionary& dict,
+    bool allowGradient,
+    bool isPointVal
+)
+:
+    debug_(dict.lookupOrDefault("debug", false)),
+    allowGradient_(allowGradient),
+    evalOnConstruct_(dict.lookupOrDefault<bool>("evalOnConstruct", false)),
+    valueExpr_(),
+    gradExpr_(),
+    fracExpr_()
+{
+    if (debug_)
+    {
+        Info<< "Expression BC with " << dict << nl;
+    }
+
+    string expr;
+
+    if (dict.readIfPresent("valueExpr", expr))
+    {
+        valueExpr_ = expressions::exprString(expr, dict);
+    }
+    else
+    {
+        // No value expression - same as Zero
+        if (debug_)
+        {
+            Info<< "No valueExpr" << nl;
+        }
+    }
+
+    if (allowGradient)
+    {
+        if (dict.readIfPresent("gradientExpr", expr))
+        {
+            gradExpr_ = expressions::exprString(expr, dict);
+        }
+        else
+        {
+            // No gradient expression - same as Zero
+
+            if (debug_)
+            {
+                Info<< "No gradientExpr" << nl;
+            }
+        }
+
+        if (dict.readIfPresent("fractionExpr", expr))
+        {
+            if (!expr.empty() && expr != "0")
+            {
+                if (isPointVal)
+                {
+                    expr = "toPoint(" + expr + ")";
+                }
+
+                fracExpr_ = expressions::exprString(expr, dict);
+            }
+        }
+        else
+        {
+            // No fraction expression - same as 1 (one)
+            // Mixed BC may elect to simply ignore gradient expression
+        }
+    }
+}
+
+
+Foam::expressions::patchExprFieldBase::patchExprFieldBase
+(
+    const patchExprFieldBase& rhs
+)
+:
+    debug_(rhs.debug_),
+    allowGradient_(rhs.allowGradient_),
+    evalOnConstruct_(rhs.evalOnConstruct_),
+    valueExpr_(rhs.valueExpr_),
+    gradExpr_(rhs.gradExpr_),
+    fracExpr_(rhs.fracExpr_)
+{}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+void Foam::expressions::patchExprFieldBase::write(Ostream& os) const
+{
+    os.writeEntryIfDifferent<bool>("evalOnConstruct", false, evalOnConstruct_);
+
+    // Do not emit debug_ value
+
+    if (!valueExpr_.empty())
+    {
+        os.writeEntry("valueExpr", valueExpr_);
+    }
+    if (!gradExpr_.empty())
+    {
+        os.writeEntry("gradientExpr", gradExpr_);
+    }
+    if (!fracExpr_.empty())
+    {
+        os.writeEntry("fractionExpr", fracExpr_);
+    }
+}
+
+
+// ************************************************************************* //

src/finiteVolume/expressions/fields/base/patchExprFieldBase.H

@@ -0,0 +1,131 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Original code Copyright (C) 2011-2018 Bernhard Gschaider
+    Copyright (C) 2019 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::expressions::patchExprFieldBase
+
+Description
+    Base class for managing patches with expressions.
+    The expected input supports values, gradients and mixed conditions
+
+Usage
+    \table
+        Property     | Description                          | Required | Default
+        valueExpr    | expression for fixed value           | no  | 0
+        gradientExpr | expression for patch normal gradient | no  | 0
+        fractionExpr | expression for value fraction weight | no  | 1
+    \endtable
+
+SourceFiles
+    patchExprFieldBase.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef expressions_patchExprFieldBase_H
+#define expressions_patchExprFieldBase_H
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#include "dictionary.H"
+#include "exprString.H"
+
+namespace Foam
+{
+
+// Forward Declarations
+class facePointPatch;
+class fvPatch;
+
+namespace expressions
+{
+
+/*---------------------------------------------------------------------------*\
+                     Class patchExprFieldBase Declaration
+\*---------------------------------------------------------------------------*/
+
+class patchExprFieldBase
+{
+protected:
+
+    // Protected Data
+
+        bool debug_;
+        bool allowGradient_;
+
+        //- Slightly dodgy concept here
+        bool evalOnConstruct_;
+
+        // The expressions
+        expressions::exprString valueExpr_;
+        expressions::exprString gradExpr_;
+        expressions::exprString fracExpr_;
+
+
+public:
+
+    // Static Methods
+
+       //- Find (guess) fvPatch from a pointPatch
+       static const fvPatch& getFvPatch(const facePointPatch& fp);
+
+
+    // Constructors
+
+        //- Null constructor
+        patchExprFieldBase();
+
+        //- Construct with specified gradient handling
+        explicit patchExprFieldBase(bool allowGradient);
+
+        //- Construct from dictionary
+        explicit patchExprFieldBase
+        (
+            const dictionary& dict,
+            bool allowGradient = false,
+            bool isPointVal = false
+        );
+
+        //- Copy constructor
+        patchExprFieldBase(const patchExprFieldBase& rhs);
+
+
+    // Member Functions
+
+        //- Write
+        void write(Ostream& os) const;
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace expressions
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/finiteVolume/expressions/fields/fvPatchFields/exprFixedValueFvPatchField.C

@@ -0,0 +1,215 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Original code Copyright (C) 2009-2018 Bernhard Gschaider
+    Copyright (C) 2019 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 "exprFixedValueFvPatchField.H"
+
+// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
+
+template<class Type>
+void Foam::exprFixedValueFvPatchField<Type>::setDebug()
+{
+    if (expressions::patchExprFieldBase::debug_ && !debug)
+    {
+        debug = 1;
+    }
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+template<class Type>
+Foam::exprFixedValueFvPatchField<Type>::exprFixedValueFvPatchField
+(
+    const fvPatch& p,
+    const DimensionedField<Type, volMesh>& iF
+)
+:
+    fixedValueFvPatchField<Type>(p, iF),
+    expressions::patchExprFieldBase(false),
+    driver_(this->patch())
+{}
+
+
+template<class Type>
+Foam::exprFixedValueFvPatchField<Type>::exprFixedValueFvPatchField
+(
+    const exprFixedValueFvPatchField<Type>& ptf,
+    const fvPatch& p,
+    const DimensionedField<Type, volMesh>& iF,
+    const fvPatchFieldMapper& mapper
+)
+:
+    fixedValueFvPatchField<Type>(ptf, p, iF, mapper),
+    expressions::patchExprFieldBase(ptf),
+    driver_(this->patch(), ptf.driver_)
+{
+    setDebug();
+    DebugInFunction << nl;
+}
+
+
+template<class Type>
+Foam::exprFixedValueFvPatchField<Type>::exprFixedValueFvPatchField
+(
+    const fvPatch& p,
+    const DimensionedField<Type, volMesh>& iF,
+    const dictionary& dict,
+    const bool valueRequired
+)
+:
+    fixedValueFvPatchField<Type>(p, iF),
+    expressions::patchExprFieldBase(dict),
+    driver_(this->patch(), dict)
+{
+    setDebug();
+    DebugInFunction << nl;
+
+    // Basic sanity
+    if (this->valueExpr_.empty())
+    {
+        FatalIOErrorInFunction(dict)
+            << "The valueExpr was not defined!" << nl
+            << exit(FatalIOError);
+    }
+
+    driver_.readDict(dict);
+
+    if (dict.found("value"))
+    {
+        fvPatchField<Type>::operator=
+        (
+            Field<Type>("value", dict, p.size())
+        );
+    }
+    else
+    {
+        (*this) == this->patchInternalField();
+
+        WarningInFunction
+            << "No value defined for "
+            << this->internalField().name() << " on "
+            << this->patch().name() << " - setting to internalField value "
+            << nl;
+    }
+
+    if (this->evalOnConstruct_)
+    {
+        // For potentialFoam or other solvers that don't evaluate
+        this->evaluate();
+    }
+}
+
+
+template<class Type>
+Foam::exprFixedValueFvPatchField<Type>::exprFixedValueFvPatchField
+(
+    const exprFixedValueFvPatchField<Type>& ptf
+)
+:
+    fixedValueFvPatchField<Type>(ptf),
+    expressions::patchExprFieldBase(ptf),
+    driver_(this->patch(), ptf.driver_)
+{
+    setDebug();
+    DebugInFunction << nl;
+}
+
+
+template<class Type>
+Foam::exprFixedValueFvPatchField<Type>::exprFixedValueFvPatchField
+(
+    const exprFixedValueFvPatchField<Type>& ptf,
+    const DimensionedField<Type, volMesh>& iF
+)
+:
+    fixedValueFvPatchField<Type>(ptf, iF),
+    expressions::patchExprFieldBase(ptf),
+    driver_(this->patch(), ptf.driver_)
+{
+    setDebug();
+    DebugInFunction << nl;
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+template<class Type>
+void Foam::exprFixedValueFvPatchField<Type>::updateCoeffs()
+{
+    if (debug)
+    {
+        InfoInFunction
+            << "Value: " << this->valueExpr_ << nl
+            << "Variables: ";
+        driver_.writeVariableStrings(Info) << endl;
+    }
+
+    if (this->updated())
+    {
+        return;
+    }
+
+    DebugInFunction
+        << "updating" << nl;
+
+    // Expression evaluation
+    {
+        driver_.clearVariables();
+
+        if (this->valueExpr_.empty())
+        {
+            (*this) == Zero;
+        }
+        else
+        {
+            tmp<Field<Type>> tresult(driver_.evaluate<Type>(this->valueExpr_));
+
+            if (debug)
+            {
+                Info<< "Evaluated: " << tresult();
+            }
+
+            (*this) == tresult;
+        }
+    }
+
+    fixedValueFvPatchField<Type>::updateCoeffs();
+}
+
+
+template<class Type>
+void Foam::exprFixedValueFvPatchField<Type>::write(Ostream& os) const
+{
+    fixedValueFvPatchField<Type>::write(os);
+    expressions::patchExprFieldBase::write(os);
+
+    // driver_.writeCommon(os, this->debug_ || debug);
+}
+
+
+// ************************************************************************* //

src/finiteVolume/expressions/fields/fvPatchFields/exprFixedValueFvPatchField.H

@@ -0,0 +1,175 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Original code Copyright (C) 2009-2018 Bernhard Gschaider
+    Copyright (C) 2019 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::exprFixedValueFvPatchField
+
+Description
+    A fixed value boundary condition with expressions.
+
+Usage
+    \table
+        Property     | Description                          | Required | Default
+        value        | fixed value                          | yes |
+        valueExpr    | expression for fixed value           | yes |
+    \endtable
+
+SourceFiles
+    exprFixedValueFvPatchField.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef exprFixedValueFvPatchField_H
+#define exprFixedValueFvPatchField_H
+
+#include "fixedValueFvPatchField.H"
+#include "patchExprFieldBase.H"
+#include "patchExprDriver.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+/*---------------------------------------------------------------------------*\
+                 Class exprFixedValueFvPatchField Declaration
+\*---------------------------------------------------------------------------*/
+
+template<class Type>
+class exprFixedValueFvPatchField
+:
+    public fixedValueFvPatchField<Type>,
+    public expressions::patchExprFieldBase
+{
+protected:
+
+    // Protected Data
+
+        //- The expression driver
+        expressions::patchExpr::parseDriver driver_;
+
+
+    // Protected Member Functions
+
+        //- Set debug ON if "debug" is enabled
+        void setDebug();
+
+
+public:
+
+    //- Runtime type information
+    TypeName("exprFixedValue");
+
+
+    // Constructors
+
+        //- Construct from patch and internal field
+        exprFixedValueFvPatchField
+        (
+            const fvPatch& p,
+            const DimensionedField<Type, volMesh>&
+        );
+
+        //- Construct from patch, internal field and dictionary
+        exprFixedValueFvPatchField
+        (
+            const fvPatch&,
+            const DimensionedField<Type, volMesh>&,
+            const dictionary& dict,
+            const bool valueRequired=true
+        );
+
+        //- Construct by mapping given exprFixedValueFvPatchField
+        //- onto a new patch
+        exprFixedValueFvPatchField
+        (
+            const exprFixedValueFvPatchField<Type>&,
+            const fvPatch&,
+            const DimensionedField<Type, volMesh>&,
+            const fvPatchFieldMapper&
+        );
+
+        //- Construct as copy
+        exprFixedValueFvPatchField
+        (
+            const exprFixedValueFvPatchField<Type>&
+        );
+
+
+        //- Construct and return a clone
+        virtual tmp<fvPatchField<Type>> clone() const
+        {
+            return tmp<fvPatchField<Type>>
+            (
+                new exprFixedValueFvPatchField<Type>(*this)
+            );
+        }
+
+        //- Construct as copy setting internal field reference
+        exprFixedValueFvPatchField
+        (
+            const exprFixedValueFvPatchField<Type>&,
+            const DimensionedField<Type, volMesh>&
+        );
+
+        //- Construct and return a clone setting internal field reference
+        virtual tmp<fvPatchField<Type>> clone
+        (
+            const DimensionedField<Type, volMesh>& iF
+        ) const
+        {
+            return tmp<fvPatchField<Type>>
+            (
+                new exprFixedValueFvPatchField<Type>(*this, iF)
+            );
+        }
+
+
+    // Member Functions
+
+        //- Update the coefficients associated with the patch field
+        virtual void updateCoeffs();
+
+        //- Write
+        virtual void write(Ostream& os) const;
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#ifdef NoRepository
+    #include "exprFixedValueFvPatchField.C"
+#endif
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/finiteVolume/expressions/fields/fvPatchFields/exprFixedValueFvPatchFields.C

@@ -0,0 +1,45 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2019 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 "exprFixedValueFvPatchFields.H"
+#include "volFields.H"
+#include "addToRunTimeSelectionTable.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+makePatchFields(exprFixedValue);
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// ************************************************************************* //

src/finiteVolume/expressions/fields/fvPatchFields/exprFixedValueFvPatchFields.H

@@ -0,0 +1,51 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2019 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/>.
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef exprFixedValueFvPatchFields_H
+#define exprFixedValueFvPatchFields_H
+
+#include "exprFixedValueFvPatchField.H"
+#include "fieldTypes.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+makePatchTypeFieldTypedefs(exprFixedValue);
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/finiteVolume/expressions/fields/fvPatchFields/exprFixedValueFvPatchFieldsFwd.H

@@ -0,0 +1,52 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2019 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/>.
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef exprFixedValueFvPatchFieldsFwd_H
+#define exprFixedValueFvPatchFieldsFwd_H
+
+#include "fieldTypes.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+template<class Type> class exprFixedValueFvPatchField;
+
+makePatchTypeFieldTypedefs(exprFixedValue);
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/finiteVolume/expressions/fields/fvPatchFields/exprMixedFvPatchField.C

@@ -0,0 +1,309 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Original code Copyright (C) 2009-2018 Bernhard Gschaider
+    Copyright (C) 2019 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 "exprMixedFvPatchField.H"
+
+// * * * * * * * * * * * * Protected Member Functions  * * * * * * * * * * * //
+
+template<class Type>
+void Foam::exprMixedFvPatchField<Type>::setDebug()
+{
+    if (expressions::patchExprFieldBase::debug_ && !debug)
+    {
+        debug = 1;
+    }
+}
+
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+template<class Type>
+Foam::exprMixedFvPatchField<Type>::exprMixedFvPatchField
+(
+    const fvPatch& p,
+    const DimensionedField<Type, volMesh>& iF
+)
+:
+    mixedFvPatchField<Type>(p, iF),
+    expressions::patchExprFieldBase(true),  // allowGradient
+    driver_(this->patch())
+{
+    this->refValue() = Zero;
+    this->refGrad() = Zero;
+    this->valueFraction() = scalar(1);
+}
+
+
+template<class Type>
+Foam::exprMixedFvPatchField<Type>::exprMixedFvPatchField
+(
+    const exprMixedFvPatchField<Type>& ptf,
+    const fvPatch& p,
+    const DimensionedField<Type, volMesh>& iF,
+    const fvPatchFieldMapper& mapper
+)
+:
+    mixedFvPatchField<Type>(ptf, p, iF, mapper),
+    expressions::patchExprFieldBase(ptf),
+    driver_(this->patch(), ptf.driver_)
+{
+    setDebug();
+    DebugInFunction << nl;
+}
+
+
+template<class Type>
+Foam::exprMixedFvPatchField<Type>::exprMixedFvPatchField
+(
+    const fvPatch& p,
+    const DimensionedField<Type, volMesh>& iF,
+    const dictionary& dict
+)
+:
+    mixedFvPatchField<Type>(p, iF),
+    expressions::patchExprFieldBase(dict, true),
+    driver_(this->patch(), dict)
+{
+    setDebug();
+    DebugInFunction << nl;
+
+    // Basic sanity checks
+    if (this->valueExpr_.empty() && this->gradExpr_.empty())
+    {
+        if (this->valueExpr_.empty())
+        {
+            FatalIOErrorInFunction(dict)
+                << "The valueExpr was not defined!" << nl
+                << exit(FatalIOError);
+        }
+        if (this->gradExpr_.empty())
+        {
+            FatalIOErrorInFunction(dict)
+                << "The gradientExpr was not defined!" << nl
+                << exit(FatalIOError);
+        }
+    }
+
+
+    driver_.readDict(dict);
+
+    // Similar to fvPatchField constructor, which we have bypassed
+    dict.readIfPresent("patchType", this->patchType());
+
+    if (dict.found("refValue"))
+    {
+        this->refValue() = Field<Type>("refValue", dict, p.size());
+    }
+    else
+    {
+        this->refValue() = this->patchInternalField();
+    }
+
+    if (dict.found("value"))
+    {
+        fvPatchField<Type>::operator=
+        (
+            Field<Type>("value", dict, p.size())
+        );
+
+        if (!dict.found("refValue"))
+        {
+            // Ensure refValue has a sensible value for the "update" below
+            this->refValue() = Field<Type>("value", dict, p.size());
+        }
+    }
+    else
+    {
+        fvPatchField<Type>::operator=(this->refValue());
+
+        WarningInFunction
+            << "No value defined for "
+            << this->internalField().name()
+            << " on " << this->patch().name() << " therefore using "
+            << "the internal field next to the patch"
+            << endl;
+    }
+
+
+    if (dict.found("refGradient"))
+    {
+        this->refGrad() = Field<Type>("refGradient", dict, p.size());
+    }
+    else
+    {
+        this->refGrad() = Zero;
+    }
+
+    if (dict.found("valueFraction"))
+    {
+        this->valueFraction() = Field<scalar>("valueFraction", dict, p.size());
+    }
+    else
+    {
+        this->valueFraction() = 1;
+    }
+
+
+    if (this->evalOnConstruct_)
+    {
+        // For potentialFoam or other solvers that don't evaluate
+        this->evaluate();
+    }
+    else
+    {
+        // Emulate mixedFvPatchField<Type>::evaluate,
+        // but avoid our own updateCoeffs
+        if (!this->updated())
+        {
+            this->mixedFvPatchField<Type>::updateCoeffs();
+        }
+
+        Field<Type>::operator=
+        (
+            this->valueFraction()*this->refValue()
+          +
+            (1.0 - this->valueFraction())*
+            (
+                this->patchInternalField()
+              + this->refGrad()/this->patch().deltaCoeffs()
+            )
+        );
+
+        fvPatchField<Type>::evaluate();
+    }
+}
+
+
+template<class Type>
+Foam::exprMixedFvPatchField<Type>::exprMixedFvPatchField
+(
+    const exprMixedFvPatchField<Type>& ptf
+)
+:
+    mixedFvPatchField<Type>(ptf),
+    expressions::patchExprFieldBase(ptf),
+    driver_(this->patch(), ptf.driver_)
+{
+    setDebug();
+    DebugInFunction << nl;
+}
+
+
+template<class Type>
+Foam::exprMixedFvPatchField<Type>::exprMixedFvPatchField
+(
+    const exprMixedFvPatchField<Type>& ptf,
+    const DimensionedField<Type, volMesh>& iF
+)
+:
+    mixedFvPatchField<Type>(ptf, iF),
+    expressions::patchExprFieldBase(ptf),
+    driver_(this->patch(), ptf.driver_)
+{
+    setDebug();
+    DebugInFunction << nl;
+}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+template<class Type>
+void Foam::exprMixedFvPatchField<Type>::updateCoeffs()
+{
+    if (debug)
+    {
+        InfoInFunction
+            << "Value: " << this->valueExpr_ << nl
+            << "Gradient: " << this->gradExpr_ << nl
+            << "Fraction: " << this->fracExpr_ << nl
+            << "Variables: ";
+
+        driver_.writeVariableStrings(Info) << endl;
+    }
+
+    if (this->updated())
+    {
+        return;
+    }
+
+    DebugInFunction << " - updating" << nl;
+
+
+    // Expression evaluation
+    {
+        driver_.clearVariables();
+
+        if (this->valueExpr_.empty())
+        {
+            this->refValue() = Zero;
+        }
+        else
+        {
+            this->refValue() = driver_.evaluate<Type>(this->valueExpr_);
+        }
+
+        bool evalGrad = !this->gradExpr_.empty();
+
+        if (this->fracExpr_.empty() || this->fracExpr_ == "1")
+        {
+            evalGrad = false;
+            this->valueFraction() = scalar(1);
+        }
+        else if (this->fracExpr_ == "0")
+        {
+            this->valueFraction() = Zero;
+        }
+        else
+        {
+            this->valueFraction() = driver_.evaluate<scalar>(this->fracExpr_);
+        }
+
+        if (evalGrad)
+        {
+            this->refGrad() = driver_.evaluate<Type>(this->gradExpr_);
+        }
+        else
+        {
+            this->refGrad() = Zero;
+        }
+    }
+
+    mixedFvPatchField<Type>::updateCoeffs();
+}
+
+
+template<class Type>
+void Foam::exprMixedFvPatchField<Type>::write(Ostream& os) const
+{
+    mixedFvPatchField<Type>::write(os);
+    expressions::patchExprFieldBase::write(os);
+
+    // driver_.writeCommon(os, this->debug_ || debug);
+}
+
+
+// ************************************************************************* //

src/finiteVolume/expressions/fields/fvPatchFields/exprMixedFvPatchField.H

@@ -0,0 +1,172 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Original code Copyright (C) 2009-2018 Bernhard Gschaider
+    Copyright (C) 2019 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::exprMixedFvPatchField
+
+Description
+    Foam::exprMixedFvPatchField
+
+Usage
+    \table
+        Property     | Description                          | Required | Default
+        valueExpr    | expression for fixed value           | no  | 0
+        gradientExpr | expression for patch normal gradient | no  | 0
+        fractionExpr | expression for value weighting       | no  | 1
+    \endtable
+
+SourceFiles
+    exprMixedFvPatchField.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef exprMixedFvPatchField_H
+#define exprMixedFvPatchField_H
+
+#include "mixedFvPatchField.H"
+#include "patchExprFieldBase.H"
+#include "patchExprDriver.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+/*---------------------------------------------------------------------------*\
+                    Class exprMixedFvPatchField Declaration
+\*---------------------------------------------------------------------------*/
+
+template<class Type>
+class exprMixedFvPatchField
+:
+    public mixedFvPatchField<Type>,
+    public expressions::patchExprFieldBase
+{
+protected:
+
+    // Protected Data
+
+        //- The expression driver
+        expressions::patchExpr::parseDriver driver_;
+
+
+    // Protected Member Functions
+
+        //- Set debug ON if "debug" is enabled
+        void setDebug();
+
+
+public:
+
+    //- Runtime type information
+    TypeName("exprMixed");
+
+
+    // Constructors
+
+        //- Construct from patch and internal field
+        exprMixedFvPatchField
+        (
+            const fvPatch& p,
+            const DimensionedField<Type, volMesh>&
+        );
+
+        //- Construct from patch, internal field and dictionary
+        exprMixedFvPatchField
+        (
+            const fvPatch&,
+            const DimensionedField<Type, volMesh>&,
+            const dictionary& dict
+        );
+
+        //- Construct by mapping given exprMixedFvPatchField onto a new patch
+        exprMixedFvPatchField
+        (
+            const exprMixedFvPatchField<Type>&,
+            const fvPatch&,
+            const DimensionedField<Type, volMesh>&,
+            const fvPatchFieldMapper&
+        );
+
+        //- Construct as copy
+        exprMixedFvPatchField
+        (
+            const exprMixedFvPatchField<Type>&
+        );
+
+        //- Construct and return a clone
+        virtual tmp<fvPatchField<Type>> clone() const
+        {
+            return tmp<fvPatchField<Type>>
+            (
+                new exprMixedFvPatchField<Type>(*this)
+            );
+        }
+
+        //- Construct as copy setting internal field reference
+        exprMixedFvPatchField
+        (
+            const exprMixedFvPatchField<Type>&,
+            const DimensionedField<Type, volMesh>&
+        );
+
+        //- Construct and return a clone setting internal field reference
+        virtual tmp<fvPatchField<Type> > clone
+        (
+            const DimensionedField<Type, volMesh>& iF
+        ) const
+        {
+            return tmp<fvPatchField<Type>>
+            (
+                new exprMixedFvPatchField<Type>(*this, iF)
+            );
+        }
+
+
+    // Member Functions
+
+        //- Update the coefficients associated with the patch field
+        virtual void updateCoeffs();
+
+        //- Write
+        virtual void write(Ostream& os) const;
+};
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#ifdef NoRepository
+    #include "exprMixedFvPatchField.C"
+#endif
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/finiteVolume/expressions/fields/fvPatchFields/exprMixedFvPatchFields.C

@@ -0,0 +1,45 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2019 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 "exprMixedFvPatchFields.H"
+#include "volFields.H"
+#include "addToRunTimeSelectionTable.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+makePatchFields(exprMixed);
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// ************************************************************************* //

src/finiteVolume/expressions/fields/fvPatchFields/exprMixedFvPatchFields.H

@@ -0,0 +1,51 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2019 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/>.
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef exprMixedFvPatchFields_H
+#define exprMixedFvPatchFields_H
+
+#include "exprMixedFvPatchField.H"
+#include "fieldTypes.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+makePatchTypeFieldTypedefs(exprMixed);
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/finiteVolume/expressions/fields/fvPatchFields/exprMixedFvPatchFieldsFwd.H

@@ -0,0 +1,52 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2019 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/>.
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef exprMixedFvPatchFieldsFwd_H
+#define exprMixedFvPatchFieldsFwd_H
+
+#include "fieldTypes.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+template<class Type> class exprMixedFvPatchField;
+
+makePatchTypeFieldTypedefs(exprMixed);
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/finiteVolume/expressions/fields/pointPatchFields/exprValuePointPatchField.C

@@ -0,0 +1,219 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Original code Copyright (C) 2010-2018 Bernhard Gschaider
+    Copyright (C) 2019 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 "exprValuePointPatchField.H"
+#include "pointPatchFieldMapper.H"
+#include "typeInfo.H"
+#include "facePointPatch.H"
+
+// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //
+
+template<class Type>
+Foam::exprValuePointPatchField<Type>::exprValuePointPatchField
+(
+    const pointPatch& p,
+    const DimensionedField<Type, pointMesh>& iF
+)
+:
+    valuePointPatchField<Type>(p, iF),
+    expressions::patchExprFieldBase(false),
+    driver_
+    (
+        expressions::patchExprFieldBase::getFvPatch
+        (
+            dynamicCast<const facePointPatch>(this->patch())
+        )
+    )
+{}
+
+
+template<class Type>
+Foam::exprValuePointPatchField<Type>::exprValuePointPatchField
+(
+    const exprValuePointPatchField<Type>& ptf,
+    const pointPatch& p,
+    const DimensionedField<Type, pointMesh>& iF,
+    const pointPatchFieldMapper& mapper
+)
+:
+    valuePointPatchField<Type>(ptf, p, iF, mapper),
+    expressions::patchExprFieldBase(ptf),
+    driver_
+    (
+        expressions::patchExprFieldBase::getFvPatch
+        (
+            dynamicCast<const facePointPatch>(this->patch())
+        ),
+        ptf.driver_
+    )
+{}
+
+
+template<class Type>
+Foam::exprValuePointPatchField<Type>::exprValuePointPatchField
+(
+    const pointPatch& p,
+    const DimensionedField<Type, pointMesh>& iF,
+    const dictionary& dict
+)
+:
+    valuePointPatchField<Type>(p, iF),
+    expressions::patchExprFieldBase(dict, false, true),
+    driver_
+    (
+        expressions::patchExprFieldBase::getFvPatch
+        (
+            dynamicCast<const facePointPatch>(this->patch())
+        ),
+        dict
+    )
+{
+    // Basic sanity
+    if (this->valueExpr_.empty())
+    {
+        FatalIOErrorInFunction(dict)
+            << "The valueExpr was not defined!" << nl
+            << exit(FatalIOError);
+    }
+
+    driver_.readDict(dict);
+
+    if (dict.found("value"))
+    {
+        Field<Type>::operator=
+        (
+            Field<Type>("value", dict, p.size())
+        );
+    }
+    else
+    {
+        WarningInFunction
+            << "No value defined for "
+            << this->internalField().name()
+            << " on " << this->patch().name()
+            << endl;
+    }
+
+    if (this->evalOnConstruct_)
+    {
+        // For potentialFoam or other solvers that don't evaluate
+        this->evaluate();
+    }
+}
+
+
+template<class Type>
+Foam::exprValuePointPatchField<Type>::exprValuePointPatchField
+(
+    const exprValuePointPatchField<Type>& ptf,
+    const DimensionedField<Type, pointMesh>& iF
+)
+:
+    valuePointPatchField<Type>(ptf, iF),
+    expressions::patchExprFieldBase(ptf),
+    driver_
+    (
+        expressions::patchExprFieldBase::getFvPatch
+        (
+            dynamicCast<const facePointPatch>(this->patch())
+        ),
+        ptf.driver_
+    )
+{}
+
+
+template<class Type>
+Foam::exprValuePointPatchField<Type>::exprValuePointPatchField
+(
+    const exprValuePointPatchField<Type>& ptf
+)
+:
+    valuePointPatchField<Type>(ptf),
+    expressions::patchExprFieldBase(ptf),
+    driver_
+    (
+        expressions::patchExprFieldBase::getFvPatch
+        (
+            dynamicCast<const facePointPatch>(this->patch())
+        ),
+        ptf.driver_
+    )
+{}
+
+
+// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //
+
+template<class Type>
+void Foam::exprValuePointPatchField<Type>::updateCoeffs()
+{
+    if (debug)
+    {
+        InfoInFunction
+            << "Value: " << this->valueExpr_ << nl
+            << "Variables: ";
+        driver_.writeVariableStrings(Info)  << endl;
+    }
+
+    if (this->updated())
+    {
+        return;
+    }
+
+    // Expression evaluation
+    {
+        driver_.clearVariables();
+
+        if (this->valueExpr_.empty())
+        {
+            (*this) == Zero;
+        }
+        else
+        {
+            Field<Type>::operator=
+            (
+                driver_.evaluate<Type>(this->valueExpr_, true)
+            );
+        }
+    }
+
+    valuePointPatchField<Type>::updateCoeffs();
+}
+
+
+template<class Type>
+void Foam::exprValuePointPatchField<Type>::write(Ostream& os) const
+{
+    valuePointPatchField<Type>::write(os);
+    expressions::patchExprFieldBase::write(os);
+
+    this->writeEntry("value",os);
+
+    // driver_.writeCommon(os,this->debug_ || debug);
+}
+
+// ************************************************************************* //

src/finiteVolume/expressions/fields/pointPatchFields/exprValuePointPatchField.H

@@ -0,0 +1,175 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Original code Copyright (C) 2010-2018 Bernhard Gschaider
+    Copyright (C) 2019 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::exprValuePointPatchField
+
+Description
+    A fixed value boundary condition with expressions.
+
+Usage
+    \table
+        Property     | Description                          | Required | Default
+        value        | fixed value                          | yes |
+        valueExpr    | expression for fixed value           | yes |
+    \endtable
+
+SourceFiles
+    exprValuePointPatchField.C
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef exprValuePointPatchField_H
+#define exprValuePointPatchField_H
+
+#include "valuePointPatchField.H"
+#include "patchExprFieldBase.H"
+#include "patchExprDriver.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+/*---------------------------------------------------------------------------*\
+                  Class exprValuePointPatchField Declaration
+\*---------------------------------------------------------------------------*/
+
+template<class Type>
+class exprValuePointPatchField
+:
+    public valuePointPatchField<Type>,
+    public expressions::patchExprFieldBase
+{
+protected:
+
+    // Protected Data
+
+        //- The expression driver
+        expressions::patchExpr::parseDriver driver_;
+
+
+public:
+
+    //- Runtime type information
+    TypeName("exprValue");
+
+
+    // Constructors
+
+        //- Construct from patch and internal field
+        exprValuePointPatchField
+        (
+            const pointPatch&,
+            const DimensionedField<Type, pointMesh>&
+        );
+
+        //- Construct from patch, internal field and dictionary
+        exprValuePointPatchField
+        (
+            const pointPatch&,
+            const DimensionedField<Type, pointMesh>&,
+            const dictionary&
+        );
+
+        //- Construct by mapping given patchField<Type> onto a new patch
+        exprValuePointPatchField
+        (
+            const exprValuePointPatchField<Type>&,
+            const pointPatch&,
+            const DimensionedField<Type, pointMesh>&,
+            const pointPatchFieldMapper&
+        );
+
+        //- Construct as copy setting internal field reference
+        exprValuePointPatchField
+        (
+            const exprValuePointPatchField<Type>&,
+            const DimensionedField<Type, pointMesh>&
+        );
+
+        //- Construct as copy
+        exprValuePointPatchField
+        (
+            const exprValuePointPatchField<Type>&
+        );
+
+
+        //- Construct and return a clone
+        virtual autoPtr<pointPatchField<Type> > clone() const
+        {
+            return autoPtr<pointPatchField<Type>>
+            (
+                new exprValuePointPatchField<Type>
+                (
+                    *this
+                )
+            );
+        }
+
+
+        //- Construct and return a clone setting internal field reference
+        virtual autoPtr<pointPatchField<Type>> clone
+        (
+            const DimensionedField<Type, pointMesh>& iF
+        ) const
+        {
+            return autoPtr<pointPatchField<Type>>
+            (
+                new exprValuePointPatchField<Type>
+                (
+                    *this,
+                    iF
+                )
+            );
+        }
+
+
+    // Member Functions
+
+        //- Update the patch field
+        virtual void updateCoeffs();
+
+        //- Write
+        virtual void write(Ostream& os) const;
+};
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#ifdef NoRepository
+#    include "exprValuePointPatchField.C"
+#endif
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //

src/finiteVolume/expressions/fields/pointPatchFields/exprValuePointPatchFields.C

@@ -0,0 +1,45 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2019 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 "exprValuePointPatchFields.H"
+#include "pointPatchFields.H"
+#include "addToRunTimeSelectionTable.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+// * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
+
+makePointPatchFields(exprValue);
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// ************************************************************************* //

src/finiteVolume/expressions/fields/pointPatchFields/exprValuePointPatchFields.H

@@ -0,0 +1,51 @@
+/*---------------------------------------------------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | www.openfoam.com
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+    Copyright (C) 2019 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/>.
+
+\*---------------------------------------------------------------------------*/
+
+#ifndef exprValuePointPatchFields_H
+#define exprValuePointPatchFields_H
+
+#include "exprValuePointPatchField.H"
+#include "fieldTypes.H"
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+namespace Foam
+{
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+makePointPatchFieldTypedefs(exprValue);
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+} // End namespace Foam
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+#endif
+
+// ************************************************************************* //