Added the interfacial pressure-work terms according to:
Ishii, M., Hibiki, T.,
Thermo-fluid dynamics of two-phase flow,
ISBN-10: 0-387-28321-8, 2006
While this is the most common approach to handling the interfacial
pressure-work it introduces numerical stability issues in regions of low
phase-fraction and rapid flow deformation. To alleviate this problem an
optional limiter may be applied to the pressure-work term in either of
the energy forms. This may specified in the
"thermophysicalProperties.<phase>" file, e.g.
pressureWorkAlphaLimit 1e-3;
which sets the pressure work term to 0 for phase-fractions below 1e-3.
For particularly unstable cases a limit of 1e-2 may be necessary.
Added 'READ_IF_PRESENT' option to support overriding of the default BCs
for complex problems requiring special treatment of Udm at boundaries.
Resolves bug-report http://bugs.openfoam.org/view.php?id=2317
In many publications and Euler-Euler codes the pressure-work term in the
total enthalpy is stated and implemented as -alpha*dp/dt rather than the
conservative form derived from the total internal energy equation
-d(alpha*p)/dt. In order for the enthalpy and internal energy equations
to be consistent this error/simplification propagates to the total
internal energy equation as a spurious additional term p*d(alpha)/dt
which is included in the OpenFOAM Euler-Euler solvers and causes
stability and conservation issues.
I have now re-derived the energy equations for multiphase flow from
first-principles and implemented in the reactingEulerFoam solvers the
correct conservative form of pressure-work in both the internal energy
and enthalpy equations.
Additionally an optional limiter may be applied to the pressure-work
term in either of the energy forms to avoid spurious fluctuations in the
phase temperature in regions where the phase-fraction -> 0. This may
specified in the "thermophysicalProperties.<phase>" file, e.g.
pressureWorkAlphaLimit 1e-3;
which sets the pressure work term to 0 for phase-fractions below 1e-3.
Previously the inlet flow of phase 1 (the phase solved for) is corrected
to match the inlet specification for that phase. However, if the second
phase is also constrained at inlets the inlet flux must also be
corrected to match the inlet specification.
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
Contributed by Juho Peltola, VTT
Notable changes:
1. The same wall function is now used for both phases, but user must
specify phaseType ‘liquid’ or ‘vapor’
2. Runtime selectable submodels for:
- wall heat flux partitioning between the phases
- nucleation site density
- bubble departure frequency
- bubble departure diameter
3. An additional iteration loop for the wall boiling model in case
the initial guess for the wall temperature proves to be poor.
The wallBoiling tutorial has been updated to demonstrate this new functionality.
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.
Required to support LTS with the -postProcess option with sub-models dependent on ddt
terms during construction, in particular reactingTwoPhaseEulerFoam.
Provides efficient integration of complex laminar reaction chemistry,
combining the advantages of automatic dynamic specie and reaction
reduction with ISAT (in situ adaptive tabulation). The advantages grow
as the complexity of the chemistry increases.
References:
Contino, F., Jeanmart, H., Lucchini, T., & D’Errico, G. (2011).
Coupling of in situ adaptive tabulation and dynamic adaptive chemistry:
An effective method for solving combustion in engine simulations.
Proceedings of the Combustion Institute, 33(2), 3057-3064.
Contino, F., Lucchini, T., D'Errico, G., Duynslaegher, C.,
Dias, V., & Jeanmart, H. (2012).
Simulations of advanced combustion modes using detailed chemistry
combined with tabulation and mechanism reduction techniques.
SAE International Journal of Engines,
5(2012-01-0145), 185-196.
Contino, F., Foucher, F., Dagaut, P., Lucchini, T., D’Errico, G., &
Mounaïm-Rousselle, C. (2013).
Experimental and numerical analysis of nitric oxide effect on the
ignition of iso-octane in a single cylinder HCCI engine.
Combustion and Flame, 160(8), 1476-1483.
Contino, F., Masurier, J. B., Foucher, F., Lucchini, T., D’Errico, G., &
Dagaut, P. (2014).
CFD simulations using the TDAC method to model iso-octane combustion
for a large range of ozone seeding and temperature conditions
in a single cylinder HCCI engine.
Fuel, 137, 179-184.
Two tutorial cases are currently provided:
+ tutorials/combustion/chemFoam/ic8h18_TDAC
+ tutorials/combustion/reactingFoam/laminar/counterFlowFlame2D_GRI_TDAC
the first of which clearly demonstrates the advantage of dynamic
adaptive chemistry providing ~10x speedup,
the second demonstrates ISAT on the modest complex GRI mechanisms for
methane combustion, providing a speedup of ~4x.
More tutorials demonstrating TDAC on more complex mechanisms and cases
will be provided soon in addition to documentation for the operation and
settings of TDAC. Also further updates to the TDAC code to improve
consistency and integration with the rest of OpenFOAM and further
optimize operation can be expected.
Original code providing all algorithms for chemistry reduction and
tabulation contributed by Francesco Contino, Tommaso Lucchini, Gianluca
D’Errico, Hervé Jeanmart, Nicolas Bourgeois and Stéphane Backaert.
Implementation updated, optimized and integrated into OpenFOAM-dev by
Henry G. Weller, CFD Direct Ltd with the help of Francesco Contino.
Contributed by Alberto Passalacqua, Iowa State University
Foam::dragModels::Beetstra
Drag model of Beetstra et al. for monodisperse gas-particle flows obtained
with direct numerical simulations with the Lattice-Boltzmann method and
accounting for the effect of particle ensembles.
Reference:
\verbatim
Beetstra, R., van der Hoef, M. A., & Kuipers, J. a. M. (2007).
Drag force of intermediate Reynolds number flow past mono- and
bidisperse arrays of spheres.
AIChE Journal, 53(2), 489–501.
\endverbatim
Foam::dragModels::Tenneti
Drag model of Tenneti et al. for monodisperse gas-particle flows obtained
with particle-resolved direct numerical simulations and accounting for the
effect of particle ensembles.
Reference:
\verbatim
Tenneti, S., Garg, R., & Subramaniam, S. (2011).
Drag law for monodisperse gas–solid systems using particle-resolved
direct numerical simulation of flow past fixed assemblies of spheres.
International Journal of Multiphase Flow, 37(9), 1072–1092.
\verbatim
to have the prefix 'write' rather than 'output'
So outputTime() -> writeTime()
but 'outputTime()' is still supported for backward-compatibility.
Also removed the redundant secondary-writing functionality from Time
which has been superseded by the 'writeRegisteredObject' functionObject.
These new names are more consistent and logical because:
primitiveField():
primitiveFieldRef():
Provides low-level access to the Field<Type> (primitive field)
without dimension or mesh-consistency checking. This should only be
used in the low-level functions where dimensional consistency is
ensured by careful programming and computational efficiency is
paramount.
internalField():
internalFieldRef():
Provides access to the DimensionedField<Type, GeoMesh> of values on
the internal mesh-type for which the GeometricField is defined and
supports dimension and checking and mesh-consistency checking.
In order to simplify expressions involving dimensioned internal field it
is preferable to use a simpler access convention. Given that
GeometricField is derived from DimensionedField it is simply a matter of
de-referencing this underlying type unlike the boundary field which is
peripheral information. For consistency with the new convention in
"tmp" "dimensionedInteralFieldRef()" has been renamed "ref()".
Non-const access to the internal field now obtained from a specifically
named access function consistent with the new names for non-canst access
to the boundary field boundaryFieldRef() and dimensioned internal field
dimensionedInternalFieldRef().
See also commit a4e2afa4b3
