By specifying the optional outside surface emissivity radiative heat transfer to
the ambient conditions is enabled.  The far-field is assumed to have an
emissivity of 1 but this could be made an optional input in the future if
needed.

Relaxation of the surface temperature is now provided via the optional
"relaxation" which aids stability of steady-state runs with strong radiative
coupling to the boundary.

with backward-compatibility so that the previous keyword "solver" is supported.

Corrected the geometry directory name from "triSurface" to "geometry".

Resolves bug-report https://bugs.openfoam.org/view.php?id=2529

Resolves bug report https://bugs.openfoam.org/view.php?id=2486

except turbulence and lagrangian which will also be updated shortly.

For example in the nonNewtonianIcoFoam offsetCylinder tutorial the viscosity
model coefficients may be specified in the corresponding "<type>Coeffs"
sub-dictionary:

transportModel  CrossPowerLaw;

CrossPowerLawCoeffs
{
    nu0         [0 2 -1 0 0 0 0]  0.01;
    nuInf       [0 2 -1 0 0 0 0]  10;
    m           [0 0 1 0 0 0 0]   0.4;
    n           [0 0 0 0 0 0 0]   3;
}

BirdCarreauCoeffs
{
    nu0         [0 2 -1 0 0 0 0]  1e-06;
    nuInf       [0 2 -1 0 0 0 0]  1e-06;
    k           [0 0 1 0 0 0 0]   0;
    n           [0 0 0 0 0 0 0]   1;
}

which allows a quick change between models, or using the simpler

transportModel  CrossPowerLaw;

nu0         [0 2 -1 0 0 0 0]  0.01;
nuInf       [0 2 -1 0 0 0 0]  10;
m           [0 0 1 0 0 0 0]   0.4;
n           [0 0 0 0 0 0 0]   3;

if quick switching between models is not required.

To support this more convenient parameter specification the inconsistent
specification of seedSampleSet in the streamLine and wallBoundedStreamLine
functionObjects had to be corrected from

    // Seeding method.
    seedSampleSet   uniform;  //cloud; //triSurfaceMeshPointSet;

    uniformCoeffs
    {
        type        uniform;
        axis        x;  //distance;

        // Note: tracks slightly offset so as not to be on a face
        start       (-1.001 -0.05 0.0011);
        end         (-1.001 -0.05 1.0011);
        nPoints     20;
    }

to the simpler

    // Seeding method.
    seedSampleSet
    {
        type        uniform;
        axis        x;  //distance;

        // Note: tracks slightly offset so as not to be on a face
        start       (-1.001 -0.05 0.0011);
        end         (-1.001 -0.05 1.0011);
        nPoints     20;
    }

which also support the "<type>Coeffs" form

    // Seeding method.
    seedSampleSet
    {
        type        uniform;

        uniformCoeffs
        {
            axis        x;  //distance;

            // Note: tracks slightly offset so as not to be on a face
            start       (-1.001 -0.05 0.0011);
            end         (-1.001 -0.05 1.0011);
            nPoints     20;
        }
    }

Radiative heat transfer may now be added to any solver in which an energy
equation is solved at run-time rather than having to change the solver code.

For example, radiative heat transfer is now enabled in the SandiaD_LTS
reactingFoam tutorial by providing a constant/fvOptions file containing

radiation
{
    type            radiation;
    libs ("libradiationModels.so");
}

and appropriate settings in the constant/radiationProperties file.

For example the porosity coefficients may now be specified thus:

porosity1
{
    type            DarcyForchheimer;

    cellZone        porosity;

    d   (5e7 -1000 -1000);
    f   (0 0 0);

    coordinateSystem
    {
        type    cartesian;
        origin  (0 0 0);
        coordinateRotation
        {
            type    axesRotation;
            e1      (0.70710678 0.70710678 0);
            e2      (0 0 1);
        }
    }
}

rather than

porosity1
{
    type            DarcyForchheimer;
    active          yes;
    cellZone        porosity;

    DarcyForchheimerCoeffs
    {
        d   (5e7 -1000 -1000);
        f   (0 0 0);

        coordinateSystem
        {
            type    cartesian;
            origin  (0 0 0);
            coordinateRotation
            {
                type    axesRotation;
                e1      (0.70710678 0.70710678 0);
                e2      (0 0 1);
            }
        }
    }
}

support for which is maintained for backward compatibility.

for consistency with the other energy sources.

For example the actuationDiskSource fvOption may now be specified

disk1
{
    type            actuationDiskSource;

    fields      (U);

    selectionMode   cellSet;
    cellSet         actuationDisk1;
    diskDir         (1 0 0);    // Orientation of the disk
    Cp              0.386;
    Ct              0.58;
    diskArea        40;
    upstreamPoint   (581849 4785810 1065);
}

rather than

disk1
{
    type            actuationDiskSource;
    active          on;

    actuationDiskSourceCoeffs
    {
        fields      (U);

        selectionMode   cellSet;
        cellSet         actuationDisk1;
        diskDir         (1 0 0);    // Orientation of the disk
        Cp              0.386;
        Ct              0.58;
        diskArea        40;
        upstreamPoint   (581849 4785810 1065);
    }
}

but this form is supported for backward compatibility.

Patch contributed by Juho Peltola, VTT.

Resolves patch request https://bugs.openfoam.org/view.php?id=2521

Main changes in the tutorial:
  - General cleanup of the phaseProperties of unnecessary entries
  - sensibleEnthalpy is used for both phases
  - setTimeStep functionObject is used to set a sharp reduction in time step near the start of the injection
  - Monitoring of pressure minimum and maximum

Patch contributed by Juho Peltola, VTT.

supporting both mesh morphing and topology change.

The standard naming convention for heat flux is "q" and this is used for the
conductive and convective heat fluxes is OpenFOAM.  The use of "Qr" for
radiative heat flux is an anomaly which causes confusion, particularly for
boundary conditions in which "Q" is used to denote power in Watts.  The name of
the radiative heat flux has now been corrected to "qr" and all models, boundary
conditions and tutorials updated.

by combining with and rationalizing functionality from
turbulentHeatFluxTemperatureFvPatchScalarField.
externalWallHeatFluxTemperatureFvPatchScalarField now replaces
turbulentHeatFluxTemperatureFvPatchScalarField which is no longer needed and has
been removed.

Description
    This boundary condition applies a heat flux condition to temperature
    on an external wall in one of three modes:

      - fixed power: supply Q
      - fixed heat flux: supply q
      - fixed heat transfer coefficient: supply h and Ta

    where:
    \vartable
        Q  | Power [W]
        q  | Heat flux [W/m^2]
        h  | Heat transfer coefficient [W/m^2/K]
        Ta | Ambient temperature [K]
    \endvartable

    For heat transfer coefficient mode optional thin thermal layer resistances
    can be specified through thicknessLayers and kappaLayers entries.

    The thermal conductivity \c kappa can either be retrieved from various
    possible sources, as detailed in the class temperatureCoupledBase.

Usage
    \table
    Property     | Description                 | Required | Default value
    mode         | 'power', 'flux' or 'coefficient' | yes |
    Q            | Power [W]                   | for mode 'power'     |
    q            | Heat flux [W/m^2]           | for mode 'flux'     |
    h            | Heat transfer coefficient [W/m^2/K] | for mode 'coefficent' |
    Ta           | Ambient temperature [K]     | for mode 'coefficient' |
    thicknessLayers | Layer thicknesses [m] | no |
    kappaLayers  | Layer thermal conductivities [W/m/K] | no |
    qr           | Name of the radiative field | no | none
    qrRelaxation | Relaxation factor for radiative field | no | 1
    kappaMethod  | Inherited from temperatureCoupledBase | inherited |
    kappa        | Inherited from temperatureCoupledBase | inherited |
    \endtable

    Example of the boundary condition specification:
    \verbatim
    <patchName>
    {
        type            externalWallHeatFluxTemperature;

        mode            coefficient;

        Ta              uniform 300.0;
        h               uniform 10.0;
        thicknessLayers (0.1 0.2 0.3 0.4);
        kappaLayers     (1 2 3 4);

        kappaMethod     fluidThermo;

        value           $internalField;
    }
    \endverbatim

Description
    Temperature-dependent surface tension model in which the surface tension
    function provided by the phase Foam::liquidProperties class is used.

Usage
    \table
        Property     | Description               | Required    | Default value
        phase        | Phase name                | yes         |
    \endtable

    Example of the surface tension specification:
    \verbatim
        sigma
        {
            type    liquidProperties;
            phase   water;
        }
    \endverbatim

for use with e.g. compressibleInterFoam, see
tutorials/multiphase/compressibleInterFoam/laminar/depthCharge2D

snappyHexMesh produces a far better quality AMI interface using a cylindrical background mesh,
leading to much more robust performance, even on a relatively coarse mesh.  The min/max AMI
weights remain close to 1 as the mesh moves, giving better conservation.

The rotating geometry template cases are configured with a blockMeshDict file for a cylindrical
background mesh aligned along the z-axis.  The details of use are found in the README and
blockMeshDict files.

Uncommenting the patches provides a convenient way to use the patches in the background mesh
to define the external boundary of the final mesh.  Replaces previous setup with a separate
blockMeshDict.extPatches file.

Combining a Function1 temperature dependency with a distributionModel stochastic
perturbation.

Resolves bug-report https://bugs.openfoam.org/view.php?id=2513

tutorials/multiphase: Removed unnecessary specification of name and dimensions for transport properties

These models have been particularly designed for use in the VoF solvers, both
incompressible and compressible.  Currently constant and temperature dependent
surface tension models are provided but it easy to write models in which the
surface tension is evaluated from any fields held by the mesh database.

Resolves bug-report https://bugs.openfoam.org/view.php?id=2514