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.
Demonstration case for three region coupling with film consisting of an
aluminium panel with surface film running down forming rivulets in a box of air
which moved due to buoyancy with 6-way thermal and velocity coupling between the
panel<->film<->air<->panel. The case runs serial and parallel with arbitrary
decomposition.
Currently extrudeToRegionMesh does not directly support three region coupling so
foamDictionary is used to edit the of the boundary files of box and film regions
to add box<->film coupling.
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.
If the optional kinematic Bingham plastic yield stress sigmay [m^2/s^2] is
provided the viscosity is updated to include the Bingham plastic correction.
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.
This fvModel applies a mass source to the continuity equation and to all
field equations, in a zero-dimensional case. Correction is made to
account for the mass that exits the domain due to expansion in space, so
that the model correctly applies a total mass flow rate. It is
implemented as a light wrapper around the massSource model.
This permits further non-conformal connnection types to store additional
or alternative information in the fvMesh::polyFacesBf patch fields.
Previously, this field just used calculated patch fields types.
This change has required an update to the fvsPatchFields to make their
handling of IO of the value field consistent with the fvPatchFields. The
base class no longer writes out the value field by default.
