The outletPhaseMeanVelocity and waveVelocity boundary conditions now
support a "ramp" keyword, for which a function can be supplied to
gradually increase the input velocity. The following is an example
specification for an outlet patch:
outlet
{
type outletPhaseMeanVelocity;
Umean 2;
ramp
{
type quarterSineRamp;
start 0;
duration 5;
}
alpha alpha.water;
}
There is also a new velocityRamping function object, which provides a
matching force within the volume of the domain, so that the entire flow
is smoothly accelerated up to the operating condition. An example
specification is as follows:
velocityRamping
{
type velocityRamping;
active on;
selectionMode all;
U U;
velocity (-2 0 0);
ramp
{
type quarterSineRamp;
start 0;
duration 5;
}
}
These additions have been designed to facilitate a smoother startup of
ship simulations by avoiding the slamming transients associated with
initialising a uniform velocity field.
This work was supported by Jan Kaufmann and Jan Oberhagemann at DNV GL.
chtMultiRegionSimpleFoam needs to check whether or not the simulation is
at the end. To facilitate this, a Time::running method has been added.
The Time::run method was being used for this purpose, but this lead to
function objects being executed multiple times.
This resolves bug report https://bugs.openfoam.org/view.php?id=2804
Using the noSlip boundary condition for rotating wall in an MRF region
interferes with post-processing by resetting the wall velocity to 0 rather than
preserving the value set by the MRF zone.
Removed possibility for the user to specify a driftRate in the constantDrift
model which is independent of a fvOptions mass source. The driftRate must be
calculated from/be consistent with the mass source in order to yield a particle
number conserving result.
Made calculation of the over-all Sauter mean diameter of an entire population
balance conditional on more than one velocityGroup being present. This diameter
field is for post-processing purposes only and would be redundant in case of one
velocityGroup being used.
Solution control is extended to allow for solution of the population balance
equation at the last PIMPLE loop only, using an optional switch. This can be
beneficial in terms of simulation time as well as coupling between the
population balance based diameter calculation and the rest of the equation
system.
Patch contributed by Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden - Rossendorf
(HZDR) and VTT Technical Research Centre of Finland Ltd.
allow renormalization of sizeGroup volume fractions for restarts involving
initial conditions with a slight degree of unboundedness
Patch contributed by Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden - Rossendorf
(HZDR) and VTT Technical Research Centre of Finland Ltd.
which provides access to the current phase and the corresponding other phase for
each of the phases in the pair. This allows some simplification of the phase
pair loops in several sub-models and avoids the need for pointer swaps.
The number of characters needed to print a double in scientific format
is 8 plus the number of decimal places; e.g., -6.453452e-231 (6 decimal
places, 14 characters). This has been set in writeFile.C, replacing a
value of 7. Presumably, the case of three digits in the exponent was not
considered when this was first implemented. This change ensures at least
one character of whitespace between tabulated numbers.
This resolves bug report https://bugs.openfoam.org/view.php?id=2801
Checking a pair contains a particular phase and adding a contribution from the
"other" phase can now be written:
if (pair.contains(phase))
{
const phaseModel& otherPhase = pair.other(phase);
phiHbyAs[phasei] +=
fvc::interpolate(rAUs[phasei]*K)
*MRF.absolute(otherPhase.phi());
HbyAs[phasei] += rAUs[phasei]*K*otherPhase.U();
}
which previously would have been written as a loop over the pair and excluding
self reference:
const phaseModel* phase1 = &pair.phase1();
const phaseModel* phase2 = &pair.phase2();
forAllConstIter(phasePair, pair, iter)
{
if (phase1 == &phase)
{
phiHbyAs[phasei] +=
fvc::interpolate(rAUs[phasei]*K)
*MRF.absolute(phase2->phi());
HbyAs[phasei] += rAUs[phasei]*K*phase2->U();
}
Swap(phase1, phase2);
}
This patch enables the reactingEulerFoam solvers to simulate polydisperse flow
situations, i.e. flows where the disperse phase is subject to a size
distribution.
The newly added populationBalanceModel class solves the integro-partial
differential population balance equation (PBE) by means of a class method, also
called discrete or sectional method. This approach is based on discretizing the
PBE over its internal coordinate, the particle volume. This yields a set of
transport equations for the number concentration of particles in classes with a
different representative size. These are coupled through their source-terms and
solved in a segregated manner. The implementation is done in a way, that the
total particle number and mass is preserved for coalescence, breakup and drift
(i.e. isothermal growth or phase change) processes, irrespective of the chosen
discretization over the internal coordinate.
A population balance can be split over multiple velocity (temperature) fields,
using the capability of reactingMultiphaseEulerFoam to solve for n momentum
(energy) equations. To a certain degree, this takes into account the dependency
of heat- and momentum transfer on the disperse phase diameter. It is also possible
to define multiple population balances, e.g. bubbles and droplets simultaneously.
The functionality can be switched on by choosing the appropriate phaseSystem
type, e.g. populationBalanceMultiphaseSystem and the newly added diameterModel
class called velocityGroup. To illustrate the use of the functionality, a
bubbleColumnPolydisperse tutorial was added for reactingTwoPhaseEulerFoam and
reactingMultiphaseEulerFoam.
Furthermore, a reactingEulerFoam-specific functionObject called sizeDistribution
was added to allow post-Processing of the size distribution, e.g. to obtain the
number density function in a specific region.
Patch contributed by Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden - Rossendorf
(HZDR) and VTT Technical Research Centre of Finland Ltd.
- Thermal phase change and wall boiling functionality has been generalized to
support two- and multi- phase simulations.
- Thermal phase change now also allows purePhaseModel, which simplifies case setup.
- The phaseSystem templates have been restructured in preparation of multiple
simultaneous mass transfer mechanisms. For example, combination of thermal phase
and inhomogeneous population balance models.
Patch contributed by VTT Technical Research Centre of Finland Ltd and Institute
of Fluid Dynamics, Helmholtz-Zentrum Dresden - Rossendorf (HZDR).
Thermo and reaction thermo macros have been renamed and refactored. If
the name is plural (make???Thermos) then it adds the model to all
selection tables. If not (make???Thermo) then it only adds to the
requested psi or rho table.
A pureMixture can now be specified in a reacting solver. This further
enhances compatibility between non-reacting and reacting solvers.
To achieve this, mixtures now have a typeName function of the same form
as the lower thermodyanmic models. In addition, to avoid name clashes,
the reacting thermo make macros have been split into those that create
entries on multiple selection tables, and those that just add to the
reaction thermo table.
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.
This mixture allows a reacting solver to be used with a single component
fluid without the additional case files usually required for reacting
thermodynamics.
The absolute value of the the time has been added to the rigid body
model state. This value is not directly necessary for calculating the
evolution of the rigid body system, it just facilitates the
implementation of sub-models which are in some way time-dependent.
The face-based momentum equation formulation introduced to twoPhaseEulerFoam by
commit 16f03f8a39 has proven particularly valuable
for bubbly flow simulations. The formulation is also available for
reactingTwoPhaseEulerFoam and this patch adds the the same capability to
reactingMultiphaseEulerFoam.
It be switched on by setting the optional faceMomentum entry in the PIMPLE
sub-dictionary in fvSolution:
PIMPLE
{
nOuterCorrectors 3;
nCorrectors 1;
nNonOrthogonalCorrectors 0;
faceMomentum yes;
}
Patch contributed by Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden - Rossendorf
(HZDR) and VTT Technical Research Centre of Finland Ltd.
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
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.
