The combustion and chemistry models no longer select and own the
thermodynamic model; they hold a reference instead. The construction of
the combustion and chemistry models has been changed to require a
reference to the thermodyanmics, rather than the mesh and a phase name.
At the solver-level the thermo, turbulence and combustion models are now
selected in sequence. The cyclic dependency between the three models has
been resolved, and the raw-pointer based post-construction step for the
combustion model has been removed.
The old solver-level construction sequence (typically in createFields.H)
was as follows:
autoPtr<combustionModels::psiCombustionModel> combustion
(
combustionModels::psiCombustionModel::New(mesh)
);
psiReactionThermo& thermo = combustion->thermo();
// Create rho, U, phi, etc...
autoPtr<compressible::turbulenceModel> turbulence
(
compressible::turbulenceModel::New(rho, U, phi, thermo)
);
combustion->setTurbulence(*turbulence);
The new sequence is:
autoPtr<psiReactionThermo> thermo(psiReactionThermo::New(mesh));
// Create rho, U, phi, etc...
autoPtr<compressible::turbulenceModel> turbulence
(
compressible::turbulenceModel::New(rho, U, phi, *thermo)
);
autoPtr<combustionModels::psiCombustionModel> combustion
(
combustionModels::psiCombustionModel::New(*thermo, *turbulence)
);
ENH: combustionModel, chemistryModel: Simplified model selection
The combustion and chemistry model selection has been simplified so
that the user does not have to specify the form of the thermodynamics.
Examples of new combustion and chemistry entries are as follows:
In constant/combustionProperties:
combustionModel PaSR;
combustionModel FSD;
In constant/chemistryProperties:
chemistryType
{
solver ode;
method TDAC;
}
All the angle bracket parts of the model names (e.g.,
<psiThermoCombustion,gasHThermoPhysics>) have been removed as well as
the chemistryThermo entry.
The changes are mostly backward compatible. Only support for the
angle bracket form of chemistry solver names has been removed. Warnings
will print if some of the old entries are used, as the parts relating to
thermodynamics are now ignored.
ENH: combustionModel, chemistryModel: Simplified model selection
Updated all tutorials to the new format
STYLE: combustionModel: Namespace changes
Wrapped combustion model make macros in the Foam namespace and removed
combustion model namespace from the base classes. This fixes a namespace
specialisation bug in gcc 4.8. It is also somewhat less verbose in the
solvers.
This resolves bug report https://bugs.openfoam.org/view.php?id=2787
ENH: combustionModels: Default to the "none" model
When the constant/combustionProperties dictionary is missing, the solver
will now default to the "none" model. This is consistent with how
radiation models are selected.
Two boundary conditions for the modelling of semi-permeable baffles have
been added. These baffles are permeable to a number of species within
the flow, and are impermeable to others. The flux of a given species is
calculated as a constant multipled by the drop in mass fraction across
the baffle.
The species mass-fraction condition requires the transfer constant and
the name of the patch on the other side of the baffle:
boundaryField
{
// ...
membraneA
{
type semiPermeableBaffleMassFraction;
samplePatch membranePipe;
c 0.1;
value uniform 0;
}
membraneB
{
type semiPermeableBaffleMassFraction;
samplePatch membraneSleeve;
c 0.1;
value uniform 1;
}
}
If the value of c is omitted, or set to zero, then the patch is
considered impermeable to the species in question. The samplePatch entry
can also be omitted in this case.
The velocity condition does not require any special input:
boundaryField
{
// ...
membraneA
{
type semiPermeableBaffleVelocity;
value uniform (0 0 0);
}
membraneB
{
type semiPermeableBaffleVelocity;
value uniform (0 0 0);
}
}
These two boundary conditions must be used in conjunction, and the
mass-fraction condition must be applied to all species in the
simulation. The calculation will fail with an error message if either is
used in isolation.
A tutorial, combustion/reactingFoam/RAS/membrane, has been added which
demonstrates this transfer process.
This work was done with support from Stefan Lipp, at BASF.
Support the following expansions when they occur at the start of a
string:
Short-form Equivalent
========= ===========
<etc>/ ~OpenFOAM/ (as per foamEtcFile)
<case>/ $FOAM_CASE/
<constant>/ $FOAM_CASE/constant/
<system>/ $FOAM_CASE/system/
These can be used in fileName expansions to improve clarity and reduce
some typing
"<constant>/reactions" vs "$FOAM_CASE/constant/reactions"
keeping chocked conditions of Mach number.
This BC can work in two modes, chocked or non-chocked. In the
chocked mode the Ma is an input. In the non-chocked mode
the Ma is calculated from model inputs.
Within decomposeParDict, it is now possible to specify a different
decomposition method, methods coefficients or number of subdomains
for each region individually.
The top-level numberOfSubdomains remains mandatory, since this
specifies the number of domains for the entire simulation.
The individual regions may use the same number or fewer domains.
Any optional method coefficients can be specified in a general
"coeffs" entry or a method-specific one, eg "metisCoeffs".
For multiLevel, only the method-specific "multiLevelCoeffs" dictionary
is used, and is also mandatory.
----
ENH: shortcut specification for multiLevel.
In addition to the longer dictionary form, it is also possible to
use a shorter notation for multiLevel decomposition when the same
decomposition method applies to each level.
- although this has been supported for many years, the tutorials
continued to use "convertToMeters" entry, which is specific to blockMesh.
The "scale" is more consistent with other dictionaries.
ENH:
- ignore "scale 0;" (treat as no scaling) for blockMeshDict,
consistent with use elsewhere.
- Use on/off vs longer compressed/uncompressed.
For consistency, replaced yes/no with on/off.
- Avoid the combination of binary/compressed,
which is disallowed and provokes a warning anyhow
Radiative heat transfer may now be added to any solver in which an energy
equation is solved at run-time rather than having to change the solver code.
For example, radiative heat transfer is now enabled in the SandiaD_LTS
reactingFoam tutorial by providing a constant/fvOptions file containing
radiation
{
type radiation;
libs ("libradiationModels.so");
}
and appropriate settings in the constant/radiationProperties file.
including support for TDAC and ISAT for efficient chemistry calculation.
Description
Eddy Dissipation Concept (EDC) turbulent combustion model.
This model considers that the reaction occurs in the regions of the flow
where the dissipation of turbulence kinetic energy takes place (fine
structures). The mass fraction of the fine structures and the mean residence
time are provided by an energy cascade model.
There are many versions and developments of the EDC model, 4 of which are
currently supported in this implementation: v1981, v1996, v2005 and
v2016. The model variant is selected using the optional \c version entry in
the \c EDCCoeffs dictionary, \eg
\verbatim
EDCCoeffs
{
version v2016;
}
\endverbatim
The default version is \c v2015 if the \c version entry is not specified.
Model versions and references:
\verbatim
Version v2005:
Cgamma = 2.1377
Ctau = 0.4083
kappa = gammaL^exp1 / (1 - gammaL^exp2),
where exp1 = 2, and exp2 = 2.
Magnussen, B. F. (2005, June).
The Eddy Dissipation Concept -
A Bridge Between Science and Technology.
In ECCOMAS thematic conference on computational combustion
(pp. 21-24).
Version v1981:
Changes coefficients exp1 = 3 and exp2 = 3
Magnussen, B. (1981, January).
On the structure of turbulence and a generalized
eddy dissipation concept for chemical reaction in turbulent flow.
In 19th Aerospace Sciences Meeting (p. 42).
Version v1996:
Changes coefficients exp1 = 2 and exp2 = 3
Gran, I. R., & Magnussen, B. F. (1996).
A numerical study of a bluff-body stabilized diffusion flame.
Part 2. Influence of combustion modeling and finite-rate chemistry.
Combustion Science and Technology, 119(1-6), 191-217.
Version v2016:
Use local constants computed from the turbulent Da and Re numbers.
Parente, A., Malik, M. R., Contino, F., Cuoci, A., & Dally, B. B.
(2016).
Extension of the Eddy Dissipation Concept for
turbulence/chemistry interactions to MILD combustion.
Fuel, 163, 98-111.
\endverbatim
Tutorials cases provided: reactingFoam/RAS/DLR_A_LTS, reactingFoam/RAS/SandiaD_LTS.
This codes was developed and contributed by
Zhiyi Li
Alessandro Parente
Francesco Contino
from BURN Research Group
and updated and tested for release by
Henry G. Weller
CFD Direct Ltd.
