The calculation of the diffusion number has been put into a form
consistent with finite-volume, rather than the finite-difference form
that was used previously.
This difference in formulations is analogus to that of the Courant
number in the fluid solvers. Whilst a textbook will typically define the
courant number as equal to 'U*deltaT/deltaX', in a finite-volume context
it is more appropriate to define it as 'Sum(phi)/V*deltaT' (where 'Sum'
is a sum over the cell's faces). Similarly, the finite-difference
Fourier number, 'kappa/rho/Cp*deltaT/deltaX^2', is more consistently
expressed for finite-volume as 'Sum(Sf*kappa*deltaX)/(V*rho*Cp)*deltaT'.
This makes the calculation of the diffusion number less sensitive to the
presence of small, poor quality faces, and therefore makes time-step
adjustment more robust on arbitrary polyhedral meshes.
Mesh motion is now supported in solid regions, but with the restriction
that it must be a solid-body-type motion. The mesh must not deform; all
cell volumes and face area magnitudes must remain constant. An error
will be generated if a motion strategy is selected that does not obey
this constraint.
This change means that even if the Courant number is zero, the time step
is adjusted based on maximum time step settings and/or constraints
specified by active fvModels. If none of these additional constraints
are present then adjustment is deactivated.
This change lets the solver be looked up from the region database, so
that aspects of the solution algorithm can be accessed by
functionObjects and fvModels and similar. For example, a fluid solver
could be looked up as follows:
const solvers::fluid& s =
mesh().lookupObject<solvers::fluid>(solver::typeName);
executed with foamRun for single region simulations of foamMultiRun for
multi-region simulations. Replaces solidDisplacementFoam and
solidEquilibriumDisplacementFoam and all the corresponding tutorials have been
updated and moved to tutorials/modules/solidDisplacement.
Class
Foam::solvers::solidDisplacement
Description
Solver module for steady or transient segregated finite-volume solution of
linear-elastic, small-strain deformation of a solid body, with optional
thermal diffusion and thermal stresses.
Solves for the displacement vector field D, also generating the stress
tensor field sigma, including the thermal stress contribution if selected.
SourceFiles
solidDisplacement.C
Some momentumTransportModels like the laminar Stokes and generalisedNewtonian
models do no solve transport equations and the transport coefficients they
provide can be predicted at the beginning of the time-step rather than corrected
at the end, after conservative fluxes are available. A particular advantage of
this approach is that complex data cached in the momentumTransportModels
can now be deleted following mesh topology changes and recreated in the
predict() call which is more efficient than attempting to register and map the
data.
Currently the predict() function is only used for the Stokes and
generalisedNewtonian models but it will be extended in the future to cover many
LES models which also do not require the solution of transport equations.
All solvers and solver modules have been update to call the
momentumTransportModel::predict() function at the beginning of the time-step,
controlled by the new PIMPLE transportPredictionFirst control as appropriate.
None of the current thermophysicalTransportModels solve transport equations in
order to evaluate the thermophysical transport properties so it makes more sense
that the evaluation occurs at the beginning of the time-step rather than at the
end where conservative fluxes are available for transport solution. To enable
this the correct() functions have been renamed predict() and called in the
prePredictor() step of foamRun and foamMultiRun and at the beginning of the
time-step in the legacy solvers. A particular advantage of this approach is
that complex data cached in the thermophysicalTransportModels can now be deleted
following mesh topology changes and recreated in the predict() call which is
more efficient than attempting to register and map the data.
An empty correct() function is included in addition to the new predict()
function in thermophysicalTransportModel to support scalar flux transport
closure in the future if needed.
Additionally the two transport model corrector function calls in foamRun and
foamMultiRun have been combined into a single postCorrector() call to allow
greater flexibility in transport property prediction and correction in the
modular solvers.
Given that the number of solid solver modules is currently 1 and unlikely to
exceed 3 it is not very useful to maintain solid and fluid sub-directories and
easier to see the correspondence between the solver modules and tutorial cases
without.
the new fluidThermophysicalTransportModel and solidThermophysicalTransportModel
are derived from thermophysicalTransportModel providing a consistent and unified
interface for heat transport within and between regions. Coupled and external
heat-transfer boundary conditions can now be written independent of the
thermophysical properties or transport modelling of the regions providing
greater flexibility, simpler code and reduces the maintenance overhead.
The previous fluidThermophysicalTransportModel typedef has been renamed
fluidThermoThermophysicalTransportModel as it is instantiated on fluidThermo,
freeing the name fluidThermophysicalTransportModel for the new base-class.
to handle isotropic and anisotropic is a consistent, general and extensible
manner, replacing the horrible hacks which were in solidThermo.
This is entirely consistent with thermophysicalTransportModel for fluids and
provides the q() and divq() for the solid energy conservation equations. The
transport model and properties are specified in the optional
thermophysicalTransport dictionary, the default model being isotropic if this
dictionary file is not present, thus providing complete backward-compatibility
for the common isotropic cases.
Anisotropic thermal conductivity is now handled in a much more general manner by
the anisotropic model:
Class
Foam::solidThermophysicalTransportModels::anisotropic
Description
Solid thermophysical transport model for anisotropic thermal conductivity
The anisotropic thermal conductivity field is evaluated from the solid
material anisotropic kappa specified in the physicalProperties dictionary
transformed into the global coordinate system using default
coordinate system and optionally additional coordinate systems specified
per-zone in the thermophysicalProperties dictionary.
Usage
Example of the anisotropic thermal conductivity specification in
thermophysicalProperties with two zone-based coordinate systems in
addition to the default:
\verbatim
model anisotropic;
// Default coordinate system
coordinateSystem
{
type cartesian;
origin (0 0 0);
coordinateRotation
{
type cylindrical;
e3 (1 0 0);
}
}
// Optional zone coordinate systems
zones
{
coil1
{
type cartesian;
origin (0.1 0.2 0.7);
coordinateRotation
{
type cylindrical;
e3 (0.5 0.866 0);
}
}
coil2
{
type cartesian;
origin (0.4 0.5 1);
coordinateRotation
{
type cylindrical;
e3 (0.866 0.5 0);
}
}
}
\endverbatim
This development required substantial rationalisation of solidThermo,
coordinateSystems and updates to the solid solver module, solidDisplacementFoam,
the wallHeatFlux functionObject, thermalBaffle and all coupled thermal boundary
conditions.
in which different solver modules can be selected in each region to for complex
conjugate heat-transfer and other combined physics problems such as FSI
(fluid-structure interaction).
For single-region simulations the solver module is selected, instantiated and
executed in the PIMPLE loop in the new foamRun application.
For multi-region simulations the set of solver modules, one for each region, are
selected, instantiated and executed in the multi-region PIMPLE loop of new the
foamMultiRun application.
This provides a very general, flexible and extensible framework for complex
coupled problems by creating more solver modules, either by converting existing
solver applications or creating new ones.
The current set of solver modules provided are:
isothermalFluid
Solver module for steady or transient turbulent flow of compressible
isothermal fluids with optional mesh motion and mesh topology changes.
Created from the rhoSimpleFoam, rhoPimpleFoam and buoyantFoam solvers but
without the energy equation, hence isothermal. The buoyant pressure
formulation corresponding to the buoyantFoam solver is selected
automatically by the presence of the p_rgh pressure field in the start-time
directory.
fluid
Solver module for steady or transient turbulent flow of compressible fluids
with heat-transfer for HVAC and similar applications, with optional
mesh motion and mesh topology changes.
Derived from the isothermalFluid solver module with the addition of the
energy equation from the rhoSimpleFoam, rhoPimpleFoam and buoyantFoam
solvers, thus providing the equivalent functionality of these three solvers.
multicomponentFluid
Solver module for steady or transient turbulent flow of compressible
reacting fluids with optional mesh motion and mesh topology changes.
Derived from the isothermalFluid solver module with the addition of
multicomponent thermophysical properties energy and specie mass-fraction
equations from the reactingFoam solver, thus providing the equivalent
functionality in reactingFoam and buoyantReactingFoam. Chemical reactions
and/or combustion modelling may be optionally selected to simulate reacting
systems including fires, explosions etc.
solid
Solver module for turbulent flow of compressible fluids for conjugate heat
transfer, HVAC and similar applications, with optional mesh motion and mesh
topology changes.
The solid solver module may be selected in solid regions of a CHT case, with
either the fluid or multicomponentFluid solver module in the fluid regions
and executed with foamMultiRun to provide functionality equivalent
chtMultiRegionFoam but in a flexible and extensible framework for future
extension to more complex coupled problems.
All the usual fvModels, fvConstraints, functionObjects etc. are available with
these solver modules to support simulations including body-forces, local sources,
Lagrangian clouds, liquid films etc. etc.
Converting compressibleInterFoam and multiphaseEulerFoam into solver modules
would provide a significant enhancement to the CHT capability and incompressible
solvers like pimpleFoam run in conjunction with solidDisplacementFoam in
foamMultiRun would be useful for a range of FSI problems. Many other
combinations of existing solvers converted into solver modules could prove
useful for a very wide range of complex combined physics simulations.
All tutorials from the rhoSimpleFoam, rhoPimpleFoam, buoyantFoam, reactingFoam,
buoyantReactingFoam and chtMultiRegionFoam solver applications replaced by
solver modules have been updated and moved into the tutorials/modules directory:
modules
├── CHT
│ ├── coolingCylinder2D
│ ├── coolingSphere
│ ├── heatedDuct
│ ├── heatExchanger
│ ├── reverseBurner
│ └── shellAndTubeHeatExchanger
├── fluid
│ ├── aerofoilNACA0012
│ ├── aerofoilNACA0012Steady
│ ├── angledDuct
│ ├── angledDuctExplicitFixedCoeff
│ ├── angledDuctLTS
│ ├── annularThermalMixer
│ ├── BernardCells
│ ├── blockedChannel
│ ├── buoyantCavity
│ ├── cavity
│ ├── circuitBoardCooling
│ ├── decompressionTank
│ ├── externalCoupledCavity
│ ├── forwardStep
│ ├── helmholtzResonance
│ ├── hotRadiationRoom
│ ├── hotRadiationRoomFvDOM
│ ├── hotRoom
│ ├── hotRoomBoussinesq
│ ├── hotRoomBoussinesqSteady
│ ├── hotRoomComfort
│ ├── iglooWithFridges
│ ├── mixerVessel2DMRF
│ ├── nacaAirfoil
│ ├── pitzDaily
│ ├── prism
│ ├── shockTube
│ ├── squareBend
│ ├── squareBendLiq
│ └── squareBendLiqSteady
└── multicomponentFluid
├── aachenBomb
├── counterFlowFlame2D
├── counterFlowFlame2D_GRI
├── counterFlowFlame2D_GRI_TDAC
├── counterFlowFlame2DLTS
├── counterFlowFlame2DLTS_GRI_TDAC
├── cylinder
├── DLR_A_LTS
├── filter
├── hotBoxes
├── membrane
├── parcelInBox
├── rivuletPanel
├── SandiaD_LTS
├── simplifiedSiwek
├── smallPoolFire2D
├── smallPoolFire3D
├── splashPanel
├── verticalChannel
├── verticalChannelLTS
└── verticalChannelSteady
Also redirection scripts are provided for the replaced solvers which call
foamRun -solver <solver module name> or foamMultiRun in the case of
chtMultiRegionFoam for backward-compatibility.
Documentation for foamRun and foamMultiRun:
Application
foamRun
Description
Loads and executes an OpenFOAM solver module either specified by the
optional \c solver entry in the \c controlDict or as a command-line
argument.
Uses the flexible PIMPLE (PISO-SIMPLE) solution for time-resolved and
pseudo-transient and steady simulations.
Usage
\b foamRun [OPTION]
- \par -solver <name>
Solver name
- \par -libs '(\"lib1.so\" ... \"libN.so\")'
Specify the additional libraries loaded
Example usage:
- To run a \c rhoPimpleFoam case by specifying the solver on the
command line:
\verbatim
foamRun -solver fluid
\endverbatim
- To update and run a \c rhoPimpleFoam case add the following entries to
the controlDict:
\verbatim
application foamRun;
solver fluid;
\endverbatim
then execute \c foamRun
Application
foamMultiRun
Description
Loads and executes an OpenFOAM solver modules for each region of a
multiregion simulation e.g. for conjugate heat transfer.
The region solvers are specified in the \c regionSolvers dictionary entry in
\c controlDict, containing a list of pairs of region and solver names,
e.g. for a two region case with one fluid region named
liquid and one solid region named tubeWall:
\verbatim
regionSolvers
{
liquid fluid;
tubeWall solid;
}
\endverbatim
The \c regionSolvers entry is a dictionary to support name substitutions to
simplify the specification of a single solver type for a set of
regions, e.g.
\verbatim
fluidSolver fluid;
solidSolver solid;
regionSolvers
{
tube1 $fluidSolver;
tubeWall1 solid;
tube2 $fluidSolver;
tubeWall2 solid;
tube3 $fluidSolver;
tubeWall3 solid;
}
\endverbatim
Uses the flexible PIMPLE (PISO-SIMPLE) solution for time-resolved and
pseudo-transient and steady simulations.
Usage
\b foamMultiRun [OPTION]
- \par -libs '(\"lib1.so\" ... \"libN.so\")'
Specify the additional libraries loaded
Example usage:
- To update and run a \c chtMultiRegion case add the following entries to
the controlDict:
\verbatim
application foamMultiRun;
regionSolvers
{
fluid fluid;
solid solid;
}
\endverbatim
then execute \c foamMultiRun
