providing the shear-stress term in the momentum equation for incompressible and
compressible Newtonian, non-Newtonian and visco-elastic laminar flow as well as
Reynolds averaged and large-eddy simulation of turbulent flow.
The general deviatoric shear-stress term provided by the MomentumTransportModels
library is named divDevTau for compressible flow and divDevSigma (sigma =
tau/rho) for incompressible flow, the spherical part of the shear-stress is
assumed to be either included in the pressure or handled separately. The
corresponding stress function sigma is also provided which in the case of
Reynolds stress closure returns the effective Reynolds stress (including the
laminar contribution) or for other Reynolds averaged or large-eddy turbulence
closures returns the modelled Reynolds stress or sub-grid stress respectively.
For visco-elastic flow the sigma function returns the effective total stress
including the visco-elastic and Newtonian contributions.
For thermal flow the heat-flux generated by thermal diffusion is now handled by
the separate ThermophysicalTransportModels library allowing independent run-time
selection of the heat-flux model.
During the development of the MomentumTransportModels library significant effort
has been put into rationalising the components and supporting libraries,
removing redundant code, updating names to provide a more logical, consistent
and extensible interface and aid further development and maintenance. All
solvers and tutorials have been updated correspondingly and backward
compatibility of the input dictionaries provided.
Henry G. Weller
CFD Direct Ltd.
These provide pressure boundary conditions suitable for use on
boundaries where the flow may reverse or on which the inlet or outlet
state is not known or well defined. The condition takes the following
form:
p = p0 + 0.5*Un*mag(Un)
In the case of exactly normal inlet velocity, this condition sets the
same pressure as the totalPressure condition. The pressure that is set
increases with increasing outlet velocity and decreases with increasing
inlet velocity. This makes it self-limiting and extremely stable in a
number of configurations which were not easily simulated previously. The
condition also does varies smoothly as the flux reverses, which also
aids stability.
The controls of this boundary condition are exactly the same as for the
totalPressure condition. Note, however, that "p0" is not necessarily the
total pressure any more. It is, in general, a reference pressure.
An example usage is as follows:
sides
{
type entrainmentPressure;
p0 100;
}
Rather than being tied to the Time class the dlLibraryTable libs is now a global
variable in the Foam namespace which is accessable by any class needing to load
dynamic libraries, in particular argList, Time and codeStream.
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.
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.
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.
and removed the need for the direct dependency of Ostream on keyType which is
not a primitive IO type and relates specifically to dictionary and not all IO.
without the need to handle the VERBATIMSTRING token type explicitly everywhere
in the IO sub-system. Having a specific type is more consistent with the design
and operation of token and much easier to maintain and extend.
The corresponding constructor in the base class was removed as part of a
number of related changes to patch field construction in commit
70021b12.
Resolves bug report https://bugs.openfoam.org/view.php?id=3304
Replaced all uses of complex Xfer class with C++11 "move" constructors and
assignment operators. Removed the now redundant Xfer class.
This substantial changes improves consistency between OpenFOAM and the C++11 STL
containers and algorithms, reduces memory allocation and copy overhead when
returning containers from functions and simplifies maintenance of the core
libraries significantly.
Using the new field mapper framework it is now possible to create specialised
mappers rather than creating a fatter and fatter interface in the base mapper.
This approach is far more extensible, comprehensible and maintainable.
Description
Surface-normal fixed value vector boundary condition
in which the vector field is obtained by scaling the patch normals
by the evaluated scalar Function1 provided.
Usage
\table
Property | Description | Required | Default value
uniformValue | uniform value | yes |
\endtable
Example of the boundary condition specification:
\verbatim
<patchName>
{
type surfaceNormalUniformFixedValue;
uniformValue constant -0.2; // 0.2 INTO the domain
}
\endverbatim
Note
Sign conventions:
- the value is positive for outward-pointing vectors
The writeEntry form is now defined and used consistently throughout OpenFOAM
making it easier to use and extend, particularly to support binary IO of complex
dictionary entries.
