so that the residualAlpha applied to stabilised the dispersed phase does not
affect the continuous phase in the limit of it becoming pure with or without
partial-elimination.
Flux correction is now applied if either the topology changed or the mesh is
moving and correctPhi is true. This strategy allows moving mesh cases without
topology change to be run without any change to the fluxes which is appropriate
for solid-body motion of the entire domain or a rotating sub-domain with NCC.
Class
Foam::solvers::functions
Description
Solver module to execute the \c functionObjects for a specified solver
The solver specified by either the \c subSolver or if not present the \c
solver entry in the \c controlDict is instantiated to provide the physical
fields needed by the \c functionObjects. The \c functionObjects are then
instantiated from the specifications are read from the \c functions entry in
the \c controlDict and executed in a time-loop also controlled by entries in
\c controlDict and the \c maxDeltaT() returned by the sub-solver.
The fields and other objects registered by the sub-solver are set to
NO_WRITE as they are not changed by the execution of the functionObjects and
should not be written out each write-time. Fields and other objects created
and changed by the execution of the functionObjects are written out.
When restarting from a time directory which does contain the \c subSolver
fields the optional \c controlDict entry \c subSolverTime may be provided to
specify which time the \c subSolver should be instantiated for, after which
time is reset to \c startTime for the restart.
to provide the old-time absolute flux. This avoids possible
pressure-velocity-flux decoupling (staggering) within the MRF region using
ddtCorr to better couple the velocity and flux fields.
These two new fvModels operate between a film and a VoF region to transfer film
to the corresponding VoF phase when the film is thick enough to be resolved by
the VoF solver or from the VoF phase to the film when the near-wall resolution
is too low and it is better to treat it as a wall film.
This functionality is equivalent to the VoFPatchTransfer fvModel developed for
the old film implementation but coded in a much more general manner with
implicit treatment of the mass loss from the film or VoF region for better
numerical stability and robustness.
The simple tutorials/modules/CHT/VoFToFilm case is provided to demonstrate a
film being deposited on a surface as the plate is withdrawn from a liquid. It
is an updated version of the tutorials/modules/compressibleVoF/plateFilm case.
Class
Foam::filmSurfaceVelocityFvPatchVectorField
Description
Film surface velocity boundary condition
Evaluates the surface velocity from the shear imposed by the neighbouring
fluid velocity using either a simple drag model based on the difference
between the fluid and film velocities multiplied by the coefficient \c Cs or
if \c Cs is not specified or set to 0 the fluid viscous shear stress.
The simple model might be used in preference to the fluid viscous shear
stress model in order to provide some means to include the drag enhancing
effect of surface ripples, rivulets etc. in the film surface.
Usage
\table
Property | Description | Required | Default value
Cs | Fluid-film drag coefficient | no | 0
\endtable
Example of the boundary condition specification using the simple drag model:
\verbatim
<patchName>
{
type filmSurfaceVelocity;
Cs 0.005;
value $internalField;
}
\endverbatim
Example of the boundary condition specification using the fluid stress:
\verbatim
<patchName>
{
type filmSurfaceVelocity;
value $internalField;
}
\endverbatim
See also
Foam::mixedFvPatchField
SourceFiles
filmSurfaceVelocityFvPatchVectorField.C
e.g. for the rivuletBox case the output for a time-step now looks like:
film Courant Number mean: 0.0003701330848 max: 0.1862204919
panel Diffusion Number mean: 0.007352456305 max: 0.1276468109
box Courant Number mean: 0.006324172752 max: 0.09030825997
deltaT = 0.001550908752
Time = 0.08294s
film diagonal: Solving for alpha, Initial residual = 0, Final residual = 0, No Iterations 0
film diagonal: Solving for alpha, Initial residual = 0, Final residual = 0, No Iterations 0
box diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
film DILUPBiCGStab: Solving for Ux, Initial residual = 0.009869417958, Final residual = 2.132619614e-11, No Iterations 2
film DILUPBiCGStab: Solving for Uy, Initial residual = 0.0002799662756, Final residual = 6.101011285e-12, No Iterations 1
film DILUPBiCGStab: Solving for Uz, Initial residual = 1, Final residual = 1.854120599e-12, No Iterations 2
box DILUPBiCGStab: Solving for Ux, Initial residual = 0.004071057403, Final residual = 4.79249226e-07, No Iterations 1
box DILUPBiCGStab: Solving for Uy, Initial residual = 0.006370817152, Final residual = 9.606673696e-07, No Iterations 1
box DILUPBiCGStab: Solving for Uz, Initial residual = 0.0158299327, Final residual = 2.104129791e-06, No Iterations 1
film DILUPBiCGStab: Solving for e, Initial residual = 0.0002888908396, Final residual = 2.301587523e-11, No Iterations 1
panel GAMG: Solving for e, Initial residual = 0.00878508958, Final residual = 7.807579738e-12, No Iterations 1
box DILUPBiCGStab: Solving for h, Initial residual = 0.004403989559, Final residual = 1.334113552e-06, No Iterations 1
film DILUPBiCGStab: Solving for alpha, Initial residual = 0.0002760406755, Final residual = 2.267583256e-14, No Iterations 1
film time step continuity errors : sum local = 9.01334987e-12, global = 2.296671859e-13, cumulative = 1.907846466e-08
box GAMG: Solving for p_rgh, Initial residual = 0.002842335602, Final residual = 1.036572819e-05, No Iterations 4
box diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
box time step continuity errors : sum local = 4.538744531e-07, global = 1.922637799e-08, cumulative = -6.612579497e-09
box GAMG: Solving for p_rgh, Initial residual = 1.283128787e-05, Final residual = 7.063185653e-07, No Iterations 2
box diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
box time step continuity errors : sum local = 3.069629869e-08, global = 3.780547824e-10, cumulative = -6.234524715e-09
ExecutionTime = 19.382601 s ClockTime = 20 s
film Courant Number mean: 0.0003684434169 max: 0.1840342756
panel Diffusion Number mean: 0.007352456305 max: 0.1276468109
box Courant Number mean: 0.006292704463 max: 0.09016861809
deltaT = 0.001550908752
Time = 0.0844909s
where each line printed by each region solver is prefixed by the region name.
Global messages for the time-step and time are just prefixed with spaces to
align them with the region output.
Class
Foam::filmSurfaceVelocityFvPatchVectorField
Description
Film surface velocity boundary condition
Evaluates the surface velocity from the shear imposed by the neighbouring
fluid velocity using a simple drag model based on the difference between the
fluid and film velocities multiplied by the coefficient \c Cs. This simple
model is used in preference to the standard viscous shear stress model in
order to provide some means to include the drag enhancing effect
of surface ripples, rivulets etc. in the film surface.
Usage
\table
Property | Description | Required | Default value
Cs | Fluid-film drag coefficient | yes |
\endtable
Example of the boundary condition specification:
\verbatim
<patchName>
{
type filmSurfaceVelocity;
Cs 0.005;
}
\endverbatim
mappedFilmPressureFvPatchScalarField is derived from the new mappedFvPatchField
base-class for mapped patch fields including mappedValueFvPatchField.
Class
Foam::mappedFilmPressureFvPatchScalarField
Description
Film pressure boundary condition which maps the neighbouring fluid patch
pressure to both the surface patch and internal film pressure field.
A new wallBoiling heat transfer model has been added for use with the
thermalPhaseChangeMultiphaseSystem. This model operates similarly to the
alphatWallBoilingWallFunction. The difference is that the boiling generated by
the wallBoiling heat transfer model occurs on the surface of a third stationary
phase, within the volume of the simulation, rather than on a wall patch. This
can be used to model boiling within a packed bed or similar.
The wallBoiling heat transfer model and the alphatWallBoilingWallFunction share
underlying sub-models, so their specification is very similar. For example, in
constant/phaseProperties:
heatTransfer
{
...
bed_dispersedIn_liquid_inThe_liquid
{
type wallBoiling;
liquidPhase liquid;
vapourPhase gas;
heatTransferModel
{
type Gunn;
}
partitioningModel
{
type Lavieville; // phaseFraction, linear, cosine
alphaCrit 0.2;
}
nucleationSiteModel
{
type LemmertChawla; // KocamustafaogullariIshii
}
departureDiameterModel
{
type TolubinskiKostanchuk; // KocamustafaogullariIshii
}
departureFrequencyModel
{
type KocamustafaogullariIshii; // Cole
Cf 1.18;
}
}
bed_dispersedIn_liquid_inThe_bed
{
type spherical;
}
...
}
Based on a patch contributed by Juho Peltola, VTT.
genericPatches is linked into mesh generation and manipulation utilities but not
solvers so that the solvers now check for the availability of the specified
patch types. Bugs in the tutorials exposed by this check have been corrected.
Class
Foam::solvers::film
Description
Solver module for flow of compressible liquid films
Uses the flexible PIMPLE (PISO-SIMPLE) solution for time-resolved and
pseudo-transient and steady simulations.
Optional fvModels and fvConstraints are provided to enhance the simulation
in many ways including adding various sources, Lagrangian particles,
radiation, surface film etc. and constraining or limiting the solution.
solvers::film is derived from solvers::isothermalFilm adding an energy equation
and temperature update with support for heat transfer to the wall using the
standard ThermophysicalTransportModels library utilising the filmWall patch type
or mappedFilmWall for CHT heat transfer to the adjacent solid region. A huge
advantage of this consistency with the rest of OpenFOAM is that the standard
thermal coupled boundary conditions can be used without modification, e.g.
temperatureCoupled.
Two variants of the rivuletPanel tutorial case are provided,
tutorials/modules/film/rivuletPanel demonstrates heat transfer to a fixed
temperature wall and tutorials/modules/CHT/rivuletPanel demonstrates conjugate
heat transfer to a thin aluminium panel simulated in a region using the
solvers::solid solver executed with solvers::film using foamMultiRun.
More functionality will be added through the power of fvModels.
Class
Foam::solvers::isothermalFilm
Description
Solver module for flow of compressible isothermal liquid films
Uses the flexible PIMPLE (PISO-SIMPLE) solution for time-resolved and
pseudo-transient and steady simulations.
Optional fvModels and fvConstraints are provided to enhance the simulation
in many ways including adding various sources, Lagrangian
particles, surface film etc. and constraining or limiting the solution.
The implementation of this new film solver is in fully conservative form,
solving for the film volume-fraction rather film thickness which ensures
conservation on curved and irregular surfaces and even around corners.
Also the formulation is consistent with standard FV solvers in other fundamental
respects using boundary conditions rather than volume forces to apply surface
stresses and transfers. This hugely advantageous approach, which allows the
reuse of many of the standard OpenFOAM libraries, in particular standard
compressibleMomentumTransportModels for the wall and internal film stresses, is
achieved using the special patch types filmWall and filmSurface to handle the
difference between the film thickness and the film cell layer height.
The specification of physical properties, boundary conditions, optional models
etc. etc. is handled in the same manner as all the other solver modules, making
much easier to use and to maintain the code.
Currently only coupling to the wall is supported with laminar transport, surface
tension, a new and more accurate contact angle algorithm and gravity which is
sufficient to demonstrate rivulet flow for example as in the tutorial case
provided: tutorials/modules/isothermalFilm/rivuletPanel
Support for coupling to an adjacent fluid region, Lagrangian impingement and
ejection, transfer to and from a VoF phase etc. will be added in the future via
the standard fvModels interface.
e.g. in extrudeToRegionMeshDict:
// Generate the region named film
region film;
// from the patch extrudeWall
patches (extrudeWall);
// generating mapped patches for the extruded region
adaptMesh yes;
// New options:
// Set the type of the mapped patch on the existing mesh to mappedWall ...
patchTypes (mappedWall);
// ... and name to wall
patchNames (wall);
// Set the type of the mapped patch on the region mesh to mappedFilmWall ...
regionPatchTypes (mappedFilmWall);
// ... and name to wall
regionPatchNames (wall);
// Set the type of the opposite patch on the region mesh to empty ...
regionOppositePatchTypes (empty);
// ... and name to empty
regionOppositePatchNames (empty);
All the above entries are optional and if not present the previous behaviour is
reproduced.
used in the alphaContactAngleFvPatchScalarField boundary condition to replace
the need to derive specialised versions for different contact angle evaluation
methods. This simplifies the code and provides a reusable system which could be
applied to other multiphase contact angle boundary conditions.
Solver modules have replaced code that was previously shared between
solvers by means of #include-ing header files. Some of these headers are
now unused and have been removed. Others are only now used in a single
solver and have been moved into that solver.
This change applies to diameter models within the multiphaseEuler
module, heat transfer fvModels, and the LopesdaCosta porosity and
turbulence models.
User input changes have been made backwards-compatible, so existing
AoV/a/Sigma/... entries and fields should continue to work.
Latent heat evaluation has been changed to calculate both sides' heats
similarly using the interface temperature, rather than using bulk
quantities on the "upwind" side of the mass transfer process
(latentHeatScheme::symmetric vs latentHeatScheme::upwind).
The transfer of heat has been changed so that it is calculated from the
mass transfer rate rather than the heat transfer coefficients and
temperatures (latentHeatTransfer::mass vs latentHeatTransfer::heat).
These changes were found to improve stability characteristics in some
boiling cases, and in general should be more energy conservative and
less dependent on the accuracy of the interfacial temeprature solution.
Patch contributed by Juho Peltola, VTT.
The new option takes a value indicating which cell types should be
written out as polyhedra. The values are as follows:
none: No polyhedral cells are written. Cells which match specific
shapes (hex, pyramid, prism, ...) are written as their
corresponding VTK cell types. Arbitrary polyhedral cells
that do not match a specific shape are decomposed into
tetrahedra.
polyhedra: Only arbitrary polyhedral cells are written as a VTK
polyhedron. Cells that match specific shapes are written as
their corresponding VTK cell types.
all: All cells are written as a VTK polyhedron.
The default is 'none', which retains the previous default behaviour.
Cell-to-cell interpolation has been moved to a hierarchy separate from
meshToMesh, called cellsToCells. The meshToMesh class is now a
combination of a cellsToCells object and multiple patchToPatch objects.
This means that when only cell-to-cell interpolation is needed a basic
cellsToCells object can be selected.
Cell-to-cell and vol-field-to-vol-field interpolation now has two well
defined sets of functions, with a clear distinction in how weights that
do not sum to unity are handled. Non-unity weights are either
normalised, or a left-over field is provided with which to complete the
weighted sum.
The left-over approach is now consistently applied in mapFieldsPar,
across both the internal and patch fields, if mapping onto an existing
field in the target case. Warning are now generated for invalid
combinations of settings, such as mapping between inconsistent meshes
without a pre-existing target field.
All mapping functions now take fields as const references and return tmp
fields. This avoids the pattern in which non-const fields are provided
which relate to the source, and at some point in the function transfer
to the target. This pattern is difficult to reason about and does not
provide any actual computational advantage, as the fields invariably get
re-allocated as part of the process anyway.
MeshToMesh no longer stores the cutting patches. The set of cutting
patches is not needed anywhere except at the point of mapping a field,
so it is now supplied to the mapping functions as an argument.
The meshToMesh topology changer no longer supports cutting patch
information. This did not previously work. Cutting patches either get
generated as calculated, or they require a pre-existing field to specify
their boundary condition. Neither of these options is suitable for a
run-time mesh change.
More code has been shared with patchToPatch, reducing duplication.
