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.
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
Formally this is equivalent to the previous formulation but more convenient to
use given that for compressible flow the mass flux rather than the volume flux
is available.
rhoSimpleFoam now instantiates the lower-level fluidThermo which instantiates
either a psiThermo or rhoThermo according to the 'type' specification in
thermophysicalProperties, e.g.
thermoType
{
type hePsiThermo;
mixture pureMixture;
transport sutherland;
thermo janaf;
equationOfState perfectGas;
specie specie;
energy sensibleInternalEnergy;
}
instantiates a psiThermo for a perfect gas with JANAF thermodynamics, whereas
thermoType
{
type heRhoThermo;
mixture pureMixture;
properties liquid;
energy sensibleInternalEnergy;
}
mixture
{
H2O;
}
instantiates a rhoThermo for water, see new tutorial
compressible/rhoSimpleFoam/squareBendLiq.
In order to support complex equations of state the pressure can no longer be
unlimited and rhoSimpleFoam now limits the pressure rather than the density to
handle start-up more robustly.
For backward compatibility 'rhoMin' and 'rhoMax' can still be used in the SIMPLE
sub-dictionary of fvSolution which are converted into 'pMax' and 'pMin' but it
is better to set either 'pMax' and 'pMin' directly or use the more convenient
'pMinFactor' and 'pMinFactor' from which 'pMax' and 'pMin' are calculated using
the fixed boundary pressure or reference pressure e.g.
SIMPLE
{
nNonOrthogonalCorrectors 0;
pMinFactor 0.1;
pMaxFactor 1.5;
transonic yes;
consistent yes;
residualControl
{
p 1e-3;
U 1e-4;
e 1e-3;
"(k|epsilon|omega)" 1e-3;
}
}
The fundamental properties provided by the specie class hierarchy were
mole-based, i.e. provide the properties per mole whereas the fundamental
properties provided by the liquidProperties and solidProperties classes are
mass-based, i.e. per unit mass. This inconsistency made it impossible to
instantiate the thermodynamics packages (rhoThermo, psiThermo) used by the FV
transport solvers on liquidProperties. In order to combine VoF with film and/or
Lagrangian models it is essential that the physical propertied of the three
representations of the liquid are consistent which means that it is necessary to
instantiate the thermodynamics packages on liquidProperties. This requires
either liquidProperties to be rewritten mole-based or the specie classes to be
rewritten mass-based. Given that most of OpenFOAM solvers operate
mass-based (solve for mass-fractions and provide mass-fractions to sub-models it
is more consistent and efficient if the low-level thermodynamics is also
mass-based.
This commit includes all of the changes necessary for all of the thermodynamics
in OpenFOAM to operate mass-based and supports the instantiation of
thermodynamics packages on liquidProperties.
Note that most users, developers and contributors to OpenFOAM will not notice
any difference in the operation of the code except that the confusing
nMoles 1;
entries in the thermophysicalProperties files are no longer needed or used and
have been removed in this commet. The only substantial change to the internals
is that species thermodynamics are now "mixed" with mass rather than mole
fractions. This is more convenient except for defining reaction equilibrium
thermodynamics for which the molar rather than mass composition is usually know.
The consequence of this can be seen in the adiabaticFlameT, equilibriumCO and
equilibriumFlameT utilities in which the species thermodynamics are
pre-multiplied by their molecular mass to effectively convert them to mole-basis
to simplify the definition of the reaction equilibrium thermodynamics, e.g. in
equilibriumCO
// Reactants (mole-based)
thermo FUEL(thermoData.subDict(fuelName)); FUEL *= FUEL.W();
// Oxidant (mole-based)
thermo O2(thermoData.subDict("O2")); O2 *= O2.W();
thermo N2(thermoData.subDict("N2")); N2 *= N2.W();
// Intermediates (mole-based)
thermo H2(thermoData.subDict("H2")); H2 *= H2.W();
// Products (mole-based)
thermo CO2(thermoData.subDict("CO2")); CO2 *= CO2.W();
thermo H2O(thermoData.subDict("H2O")); H2O *= H2O.W();
thermo CO(thermoData.subDict("CO")); CO *= CO.W();
// Product dissociation reactions
thermo CO2BreakUp
(
CO2 == CO + 0.5*O2
);
thermo H2OBreakUp
(
H2O == H2 + 0.5*O2
);
Please report any problems with this substantial but necessary rewrite of the
thermodynamic at https://bugs.openfoam.org
Henry G. Weller
CFD Direct Ltd.
The spherical part of the Reynolds stress is included in the pressure so
that the wall boundary condition for the pressure is zeroGradient.
Resolves bug-report http://bugs.openfoam.org/view.php?id=2325
to handle the size of bubbles created by boiling. To be used in
conjunction with the alphatWallBoilingWallFunction boundary condition.
The IATE variant of the wallBoiling tutorial case is provided to
demonstrate the functionality:
tutorials/multiphase/reactingTwoPhaseEulerFoam/RAS/wallBoilingIATE
to ensure 'patchType' is set as specified.
Required substantial change to the organization of the reading of the
'value' entry requiring careful testing and there may be some residual
issues remaining. Please report any problems with the reading and
initialization of patch fields.
Resolves bug-report http://bugs.openfoam.org/view.php?id=2266
Renamed the original 'laminar' model to 'Stokes' to indicate it is a
linear stress model supporting both Newtonian and non-Newtonian
viscosity.
This general framework will support linear, non-linear, visco-elastic
etc. laminar transport models.
For backward compatibility the 'Stokes' laminar stress model can be
selected either the original 'laminar' 'simulationType'
specification in turbulenceProperties:
simulationType laminar;
or using the new more general 'laminarModel' specification:
simulationType laminar;
laminar
{
laminarModel Stokes;
}
which allows other laminar stress models to be selected.
Changed default mode of operation to use standard y+ based switching
rather than the previous ad hoc blending and added consistent handling
of the near-wall generation term.
This boundary condition provides a wall constraint on turbulnce specific
dissipation, omega for both low and high Reynolds number turbulence models.
The near-wall omega may be either blended between the viscous region and
logarithmic region values using:
\f[
\omega = sqrt(\omega_{vis}^2 + \omega_{log}^2)
\f]
where
\vartable
\omega_{vis} | omega in viscous region
\omega_{log} | omega in logarithmic region
\endvartable
see eq.(15) of:
\verbatim
Menter, F., Esch, T.
"Elements of Industrial Heat Transfer Prediction"
16th Brazilian Congress of Mechanical Engineering (COBEM),
Nov. 2001
\endverbatim
or switched between these values based on the laminar-to-turbulent y+ value
derived from kappa and E. Recent tests have shown that the standard
switching method provides more accurate results for 10 < y+ < 30 when used
with high Reynolds number wall-functions and both methods provide accurate
results when used with continuous wall-functions. Based on this the
standard switching method is used by default.
This boundary condition provides a turbulence dissipation wall constraint
for low- and high-Reynolds number turbulence models.
The condition can be applied to wall boundaries for which it
- calculates \c epsilon and \c G
- specifies the near-wall epsilon value
where
\vartable
epsilon | turblence dissipation field
G | turblence generation field
\endvartable
The model switches between laminar and turbulent functions based on the
laminar-to-turbulent y+ value derived from kappa and E.
Recent tests have shown that this formulation is more accurate than
the standard high-Reynolds number form for 10 < y+ < 30 with both
standard and continuous wall-functions.
Replaces epsilonLowReWallFunction and should be used for all
low-Reynolds number models for which the epsilonLowReWallFunction BC was
recommended.
Description
Langtry-Menter 4-equation transitional SST model
based on the k-omega-SST RAS model.
References:
Langtry, R. B., & Menter, F. R. (2009).
Correlation-based transition modeling for unstructured parallelized
computational fluid dynamics codes.
AIAA journal, 47(12), 2894-2906.
Menter, F. R., Langtry, R., & Volker, S. (2006).
Transition modelling for general purpose CFD codes.
Flow, turbulence and combustion, 77(1-4), 277-303.
Langtry, R. B. (2006).
A correlation-based transition model using local variables for
unstructured parallelized CFD codes.
Phd. Thesis, Universität Stuttgart.
Implemented by Henry G. Weller, CFD Direct in collaboration with Florian
Schwertfirm, Kreuzinger und Manhart Turbulenz GmbH.
updateCoeffs(const scalarField&) -> updateWeightedCoeffs(const scalarField&)
to avoid confusion with other specialized forms of updateCoeffs.
Patch contributed by Mattijs Janssens
Description
Implementation of the k-omega-SST-DES turbulence model for
incompressible and compressible flows.
DES model described in:
\verbatim
Menter, F. R., Kuntz, M., and Langtry, R. (2003).
Ten Years of Industrial Experience with the SST Turbulence Model.
Turbulence, Heat and Mass Transfer 4, ed: K. Hanjalic, Y. Nagano,
& M. Tummers, Begell House, Inc., 625 - 632.
\endverbatim
Optional support for zonal filtering based on F1 or F2 is provided as
described in the paper.
For further details of the implementation of the base k-omega-SST model
see Foam::kOmegaSST.
The DES coefficient 'CDES' defaults to 0.61 but may be changed as
necessary.
The zonal filter filter defaults to '2' which uses "(1 - F2)" as
suggested in the paper but '0' (no filtering) and '1' which uses
"(1 - F1)" are also supported.
