For many information and diagnostic messages the absolute path of the object is
not required and the local path relative to the current case is sufficient; the
new localObjectPath() member function of IOobject provides a convenient way of
printing this.
The calculation and input/output of transformations has been rewritten
for all coupled patches. This replaces multiple duplicated, inconsistent
and incomplete implementations of transformation handling which were
spread across the different coupled patch types.
Transformations are now calculated or specified once, typically during
mesh construction or manipulation, and are written out with the boundary
data. They are never re-calculated. Mesh changes should not change the
transformation across a coupled interface; to do so would violate the
transformation.
Transformations are now calculated using integral properties of the
patches. This is more numerically stable that the previous methods which
functioned in terms of individual faces. The new routines are also able
to automatically calculate non-zero centres of rotation.
The user input of transformations is backwards compatible, and permits
the user to manually specify varying amounts of the transformation
geometry. Anything left unspecified gets automatically computed from the
patch geometry. Supported specifications are:
1) No specification. Transformations on cyclics are automatically
generated, and cyclicAMI-type patches assume no transformation. For
example (in system/blockMeshDict):
cyclicLeft
{
type cyclic;
neighbourPatch cyclicRight;
faces ((0 1 2 3));
}
cyclicRight
{
type cyclic;
neighbourPatch cyclicLeft;
faces ((4 5 6 7));
}
2) Partial specification. The type of transformation is specified
by the user, as well as the coordinate system if the transform is
rotational. The rotation angle or separation vector is still
automatically generated. This form is useful as the signs of the
angle and separation are opposite on different sides of an interface
and can be difficult to specify correctly. For example:
cyclicLeft
{
type cyclic;
neighbourPatch cyclicRight;
transformType translational;
faces ((0 1 2 3));
}
cyclicRight
{
type cyclic;
neighbourPatch cyclicLeft;
transformType translational;
faces ((4 5 6 7));
}
cyclicAMILeft
{
type cyclicAMI;
neighbourPatch cyclicAMIRight;
transformType rotational;
rotationAxis (0 0 1);
rotationCentre (0.05 -0.01 0);
faces ((8 9 10 11));
}
cyclicAMIRight
{
type cyclicAMI;
neighbourPatch cyclicAMILeft;
transformType rotational;
rotationAxis (0 0 1);
rotationCentre (0.05 -0.01 0);
faces ((12 13 14 15));
}
3) Full specification. All parameters of the transformation are
given. For example:
cyclicLeft
{
type cyclic;
neighbourPatch cyclicRight;
transformType translational;
separaion (-0.01 0 0);
faces ((0 1 2 3));
}
cyclicRight
{
type cyclic;
neighbourPatch cyclicLeft;
transformType translational;
separaion (0.01 0 0);
faces ((4 5 6 7));
}
cyclicAMILeft
{
type cyclicAMI;
neighbourPatch cyclicAMIRight;
transformType rotational;
rotationAxis (0 0 1);
rotationCentre (0.05 -0.01 0);
rotationAngle 60;
faces ((8 9 10 11));
}
cyclicAMIRight
{
type cyclicAMI;
neighbourPatch cyclicAMILeft;
transformType rotational;
rotationAxis (0 0 1);
rotationCentre (0.05 -0.01 0);
rotationAngle 60;
faces ((12 13 14 15));
}
Automatic ordering of faces and points across coupled patches has also
been rewritten, again replacing multiple unsatisfactory implementations.
The new ordering method is more robust on poor meshes as it
geometrically matches only a single face (per contiguous region of the
patch) in order to perform the ordering, and this face is chosen to be
the one with the highest quality. A failure in ordering now only occurs
if the best face in the patch cannot be geometrically matched, whether
as previously the worst face could cause the algorithm to fail.
The oldCyclicPolyPatch has been removed, and the mesh converters which
previously used it now all generate ordered cyclic and baffle patches
directly. This removes the need to run foamUpgradeCyclics after
conversion. In addition the fluent3DMeshToFoam converter now supports
conversion of periodic/shadow pairs to OpenFOAM cyclic patches.
For complex geometries the calculation of surface face and point "closeness" can
be quite time consuming and usually only one or other is required; the new
options allow the user to specify which should be calculated and written.
The source update counter is now always initialised to zero. Previously
an attempt was made to determine the current number of iterations
reached so that on restart the source updates occur at the same
intervals as they would have had the simulation not been stopped. The
problem with this is that the sources themselves are not stored to disk,
so on restart a simulation could progress for quite some time before the
sources were properly initialised at the next update.
Resetting the counter to zero does not give a perfect restart (i.e., as
if the simulation had continued without stopping), but it does provide a
stable and consistent solution sequence. Perfect restart could only be
achieved with this iteration procedure by writing all the sources to
disk and reading them back in again. This is considered a worse
compromise due to the amount of disk space that it would require.
Patch contributed by Timo Niemi, VTT.
The thermal phase system now operates with saturation models specified
per phase-pair, and can therefore represent multiple transfer processes
across different interfaces. There is no longer a "phaseChange" switch;
instead the selection of a saturation model for a given interface
enables phase change across that interface. This includes both
interfacial phase change and nucleate wall boiling.
Both interfacial phase change and wall boiling models now include
support for there being a single specified volatile component which
undergoes phase change.
A correction has been made to the phase change energy transfer when only
interfacial phase change is enabled.
The thermal phase change tutorials have all been updated to reflect
these changes in the user interface.
Patch contributed by Juho Peltola, VTT.
A single transformer object is now maintained within cyclic patches and returned
from a single virtual functions massively simplifying the interface and allowing
for further rationalisation of the calculation of the transformation.
The implementation of the optional non-uniform transformations in coupled
patches was based on transform property lists which could be either length 0 for
no transformation, 1 for uniform transformation or n-faces for non-uniform
transformation. This complexity was maintenance nightmare but kept to support
the hack in the original film implementation to partially work around the
conservation error. Now that film has been re-implemented in fully mass
conservative form this unphysical non-uniform transformation support is no
longer needed and the coupled patch transformations have been completely
refactored to be simpler and more rational with single values for the
transformation properties and boolians to indicate which transformations are
needed.
The kOmegaSSTSata model can now be used in multiphase cases, provided
that there is a single, well defined continuous phase. As previously,
the continuous phase is the phase for which the model is selected (i.e.,
in the constant/turbulenceProperties.<continuous-phase-name>
dictionary).
By default, now, all other moving phases are considered to be dispersed
bubble phases, and the effect of all of them is summed to calculate the
overall bubble induced turbulence.
This behaviour can be overridden by means of a "dispersedPhases" entry,
which takes a list of the phases to be considered dispersed by the
model.
Patch contributed by Timo Niemi, VTT.
The correction of thermodynamics, reactions, and the enforcement of the
specie fraction sum are now done in the same sequence as other reacting
solvers.
Patch contributed by Juho Peltola, VTT.
All of the film transport equations are now formulated with respect to the film
volume fraction in the region cell layer rather than the film thickness which
ensures mass conservation of the film even as it flows over curved surfaces and
around corners. (In the previous formulation the conservation error could be as
large as 15% for a film flowing around a corner.)
The film Courant number is now formulated in terms of the film cell volumetric
flux which avoids the stabilised division by the film thickness and provides a
more reliable estimate for time-step evaluation. As a consequence the film
solution is substantially more robust even though the time-step is now
significantly higher. For film flow dominated problem the simulations now runs
10-30x faster.
The inconsistent extended PISO controls have been replaced by the standard
PIMPLE control system used in all other flow solvers, providing consistent
input, a flexible structure and easier maintenance.
The momentum corrector has been re-formulated to be consistent with the momentum
predictor so the optional PIMPLE outer-corrector loop converges which it did not
previously.
nonuniformTransformCyclic patches and corresponding fields are no longer needed
and have been removed which paves the way for a future rationalisation of the
handling of cyclic transformations in OpenFOAM to improve robustness, usability
and maintainability.
Film sources have been simplified to avoid the need for fictitious boundary
conditions, in particular mappedFixedPushedInternalValueFvPatchField which has
been removed.
Film variables previously appended with an "f" for "film" rather than "face"
have been renamed without the unnecessary and confusing "f" as they are
localised to the film region and hence already directly associated with it.
All film tutorials have been updated to test and demonstrate the developments
and improvements listed above.
Henry G. Weller
CFD Direct Ltd.
Corrected call to model2In1 in one of the evaluate methods
Patch contributed by Institute of Fluid Dynamics,
Helmholtz-Zentrum Dresden - Rossendorf (HZDR)
This fix ensures that the function still operates even if models only
exist on some interfaces.
Patch contributed by Institute of Fluid Dynamics,
Helmholtz-Zentrum Dresden - Rossendorf (HZDR)
functionEntry expansion is enabled for dictionary expansion with the -expand
option. The disableFunctionEntries option is no longer needed and has been removed.
The update of mass transfer rates in the population balance system is
now done at the same time as other source terms. This benefits
synchronisation of the mass transfer rate and the source terms and
prevents the system converging to an incorrect state.
Patch contributed by VTT Technical Research Centre of Finland Ltd and
Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden - Rossendorf (HZDR).
In order to improve stability and robustness of fluidised bed cases the
semi-implicit treatment of the particle pressure (pPrime) is now applied within
the time-step sub-cycling along with the phase differential flux update. This
allows the simulations to be performed reliably at a significantly increased
maximum Courant number (up to 5 for some cases) without introducing
chequerboarding patterns in regions of low particle phase fraction which
occurred with the previous algorithm.
The fluidisedBed tutorial has been updated to be more representative of real
bubbling bed cases and to demonstrate the new pPrime functionality.
Developed in collaboration with Timo Niemi, VTT.
derived from solidThermo. This allows the standard heat transfer boundary
conditions, for example externalWallHeatFluxTemperature, to be used with
solidDisplacementFoam and also significantly simplifies the code.
Additionally solidDisplacementFoam and solidEquilibriumDisplacementFoam have
been updated to handle spatially varying physical properties in a conservative
manner both for the stress and heat transfer. This means that the stress field
sigma is now dynamic rather than kinematic as it was previously. For uniform
property fields the behaviour of the solvers is the same as it was before this
update.
This changes improves the update of the pPrime contribution from the particle
interaction pressure in the optional phase fraction corrector loop in
reactingTwoPhaseEulerFoam particularly for fluidized bed simulations with a hard
packing limit.
Multiphase support is also added for the optional implicit treatment of
turbulent dispersion in the phase fraction equations which will also be
applicable to particle packing when multiphase handing of kinetic theory is
added.
The pressure provided to the patch and cellSet property evaluation functions is
always that stored by the thermodynamics package as is the composition which is
provided internally; given that these functions are used in boundary conditions
to estimate changes in heat flux corresponding to changes in temperature only
there is no need for another pressure to be provided. In order that the
pressure and composition treatment are consistent and to maintain that during
future rationalisation of the handling of composition it makes sense to remove
this unnecessary pressure argument.
This part of the name is unnecessary, as it is clear from context that
the name refers to a reaction. The selector has been made backwards
compatible so that old names will still read successfuly.
Function1 has been generalised in order to provide functionality
previously provided by some near-duplicate pieces of code.
The interpolationTable and tableReader classes have been removed and
their usage cases replaced by Function1. The interfaces to Function1,
Table and TableFile has been improved for the purpose of using it
internally; i.e., without user input.
Some boundary conditions, fvOptions and function objects which
previously used interpolationTable or other low-level interpolation
classes directly have been changed to use Function1 instead. These
changes may not be backwards compatible. See header documentation for
details.
In addition, the timeVaryingUniformFixedValue boundary condition has
been removed as its functionality is duplicated entirely by
uniformFixedValuePointPatchField.
In two phases, the turbulent dispersion force is modelled for a phase
pair as follows:
F12 = D12*grad(alpha1)
Where D12 is the turbulent dispersion coefficient between phases 1 and
2. This force is calculated equivalently whichever phase is chosen to be
phase 1 because the volume fractions are related by alpha1 = 1 - alpha2.
This means that F12 == - F21; i.e., the force in one phase equals the
reaction in the other.
In multiple phases, however, a force calculated in this way is no longer
consistent between phases, because the relationship between the volume
fractions no longer applies. The following form has been chosen instead.
F12 = D12*grad(alpha1/(alpha1 + alpha2))
I.e., rather than using the gradient of a phase directly, we use the
gradient of the phase within the two-phase sub-system associated with
the pair.
This reduces to the two-phase case above, and the models available in
the literature that are explicitly formulated for multiple phases can
also be expressed in this form.
Based on a patch contributed by Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden -
Rossendorf (HZDR) and VTT Technical Research Centre of Finland Ltd.
Integral evaluations have been implemented for all the ramp function1-s,
as well as the sine and square wave. Bounds handling has also been added
to the integration of table-type functions.
In addition, the sine wave "t0" paramater has been renamed "start" for
consistency with the ramp functions.
Description
Gunn (1978) correlation for fixed and fluidized beds with Re < 10^5
and continuous phase fraction between 0.35 and 1.
Reference:
\verbatim
Gunn, D. J. (1978).
Transfer of heat or mass to particles in fixed and fluidised beds.
International Journal of Heat and Mass Transfer, 21(4), 467-476.
\endverbatim
Based on code contributed by Alberto Passalacqua
