including third-body and pressure dependent derivatives, and derivative of the
temperature term. The complete Jacobian is more robust than the incomplete and
partially approximate form used previously and improves the efficiency of the
stiff ODE solvers which rely on the Jacobian.
Reaction rate evaluation moved from the chemistryModel to specie library to
simplfy support for alternative reaction rate expressions and associated
Jacobian terms.
Temperature clipping included in the Reaction class. This is inactive by default
but for most cases it is advised to provide temperature limits (high and
low). These are provided in the foamChemistryFile with the keywords Thigh and
Tlow. When using chemkinToFoam these values are set to the limits of the Janaf
thermodynamic data. With the new Jacobian this temperature clipping has proved
very beneficial for stability and for some cases essential.
Improvement of the TDAC MRU list better integrated in add and grow functions.
To get the most out of this significant development it is important to re-tune
the ODE integration tolerances, in particular the absTol in the odeCoeffs
sub-dictionary of the chemistryProperties dictionary:
odeCoeffs
{
solver seulex;
absTol 1e-12;
relTol 0.01;
}
Typically absTol can now be set to 1e-8 and relTol to 0.1 except for ignition
time problems, and with theses settings the integration is still robust but for
many cases a lot faster than previously.
Code development and integration undertaken by
Francesco Contino
Henry G. Weller, CFD Direct
twoPhaseMixtureThermo writes the temperatures during construction only
for them to be read again immediately after by construction of the
individual phases' thermo models. When running with collated file
handling this behaviour is not thread safe. This change deactivates
threading for the duration of this behaviour.
Patch contributed by Mattijs Janssens
The reference height is now defined in the direction of -g, whether as
previously it was defined in the direction cmptMag(g). This change makes
the behaviour consistent when the case is transformed. For a "typical"
case with g along one of the negative axes, this should make no
difference. None of the tutorials are affected.
Resolves bug report https://bugs.openfoam.org/view.php?id=2980
This is faster than the library functionality that it replaces, as it
allows the compiler to do inlining. It also does not utilise any static
state so generators do not interfere with each other. It is also faster
than the the array lookup in cachedRandom. The cachedRandom class
therefore offers no advantage over Random and has been removed.
Tree bound boxes are expanded asymmetrically to reduce the liklihood of
octree faces aliging with mesh faces and edges. The asymmetry is now
generated using hard-coded irrational numbers, rather than using a
random generator.
The asymmetry was effectively already hard coded. The random numbers are
only pseudo random, so the same numbers were being applied to the bound
boxes every time. This change simply removes the overhead of creating
the generator, and also gets rid of some duplicated code.
Changed the default region name from "domain" to "region" for consistency with
the rest of OpenFOAM.
Changed the multiple default region numbering to start from 1 rather than 0
because the top-level mesh in the case directory is always named "region0".
Changed the default region numbering to only relate to the default named regions
and does not increment for explicitly named regions. This avoids a naming
dependency on the default and named region order.
Added new option "-defaultRegionName <name>"
to specify the base name of the unspecified regions, defaults to "region"
The handling of species transfer within the interface-composition phase
change system has been sigificantly altered. The explicit-implicit
caching of the mass transfer has been removed and been replaced with
storage of an Su-Sp coefficient pair. The mass transfer is now generated
on the fly from these coefficients.
These fixes resolve a number of issues involving multiple species for
which the pimple loop did not converge to a conservative solution. It
also removes the requirement for a second evaluation of the mass
transfer after solution of the species fraction equations.
This work was supported by Zhen Li, at Evonik
This fixes a consistency issue in the interface-composition method, and
also seems to improve stability/convergence of the pimple iteration in
the presence of significant mass transfer.
