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.
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.
The new patch field mapping class timeVaryingMappedFvPatchField has been
factored out of the timeVaryingMappedFixedValueFvPatchField BC so that it can be
used to map data onto fields stored within other BCs.
In the process the writeEntryIfDifferent function had to be moved from
fvPatchField to dictionary so that it can still be used in the
timeVaryingMappedFvPatchField class and it made good sense to create the
non-conditional variant writeEntry to simplify the patch field write functions.
This rationalisation has been propagated all other patch fields.
This is an inlet-outlet condition where the inlet value differs above
and below a wave interface. It can be used as follows:
inlet
{
type waveInletOutlet;
inletValueAbove 0.01;
inletValueBelow 0.1;
}
With the inclusion of boundary layer modelling in the gas, the
separation of wave perturbation from and mean flow became less useful,
and potentially prevents further extension to support similar boundary
layer modelling in the liquid.
The mean velocity entry, UMean, is now needed in the
constant/waveProperties file rather than in the waveVelocity boundary
condition.
An atmospheric boundary layer velocity can now be added to the gas side
of the wave modelling. The wave superposition class has been given a
run-time selection mechanism, and a derivation added which includes gas
atmospheric boundary layer modelling. This modelling is therefore
available in both the wave boundary conditions, and in setWaves.
This functionality can be selected in the constant/waveProperties file
by supplying a "type" entry and a number of parameters controlling the
boundary layer. For example:
In constant/waveProperties:
type waveAtmBoundaryLayer;
// properties specifying the wave modelling ...
UGasRef (10 0 0);
hRef 20;
hWaveMin -2;
hWaveMax 3;
UGasRef is the gas velocity relative to the liquid, at the height, hRef,
relative to the wave model origin. hWaveMin and hWaveMax describe the
range of the wave elevation; it is non-trivial to calculate this from
the wave models themselves, so it is required as an input.
The base wave superposition class can be selected with "type wave;", but
also selects by default when the "type" entry is omitted, so the change
is backwards compatible.
In order to increase the flexibility of the wave library, the mean flow
handling has been removed from the waveSuperposition class. This makes
waveSuperposition work purely in terms of perturbations to a mean
background flow.
The input has also been split, with waves now defined as region-wide
settings in constant/waveProperties. The mean flow parameters are sill
defined by the boundary conditions.
The new format of the velocity boundary is much simpler. Only a mean
flow velocity is required.
In 0/U:
boundaryField
{
inlet
{
type waveVelocity;
UMean (2 0 0);
}
// etc ...
}
Other wave boundary conditions have not changed.
The constant/waveProperties file contains the wave model selections and
the settings to define the associated coordinate system and scaling
functions:
In constant/waveProperties:
origin (0 0 0);
direction (1 0 0);
waves
(
Airy
{
length 300;
amplitude 2.5;
phase 0;
angle 0;
}
);
scale table ((1200 1) (1800 0));
crossScale constant 1;
setWaves has been changed to use a system/setWavesDict file rather than
relying on command-line arguments. It also now requires a mean velocity
to be specified in order to prevent ambiguities associated with multiple
inlet patches. An example is shown below:
In system/setWavesDict:
alpha alpha.water;
U U;
liquid true;
UMean (1 0 0);
An "inletOutlet" switch has been added to the wave velocity boundary
condition to allow the boundary to be fixed, as is possible for the
corresponding alpha condition.
A "heightAboveWave" option has been added to the wave superposition
class to calculate velocity based on the height above the wave, rather
than above the origin. This may improve initialisation but it may also
generate divergence in the initial velocity field.
The alpha condition has also been completed so that it applies a
modelled gradient when the flow points out and a wave pressure condition
is in use.
In early versions of OpenFOAM the scalar limits were simple macro replacements and the
names were capitalized to indicate this. The scalar limits are now static
constants which is a huge improvement on the use of macros and for consistency
the names have been changed to camel-case to indicate this and improve
readability of the code:
GREAT -> great
ROOTGREAT -> rootGreat
VGREAT -> vGreat
ROOTVGREAT -> rootVGreat
SMALL -> small
ROOTSMALL -> rootSmall
VSMALL -> vSmall
ROOTVSMALL -> rootVSmall
The original capitalized are still currently supported but their use is
deprecated.
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.
A wavePressure boundary condition has been added, and the Airy-type wave
models have been extended to generate the unsteady pressure field. This
provides another option for specifying wave motion at a boundary.
If a waveVelocity condition is used in isolation, then any outlet flow
will be extrapolated and scaled to match the required flow rate. This is
similar to how a flowRateOutletVelocity condition works.
0/U:
<patchName>
{
type waveVelocity;
// wave parameters ...
}
0/p_rgh:
<patchName>
{
type fixedFluxPressure;
}
If a waveVelocity is used in conjunction with the new wavePressure
condition, then one will set the value and the other the gradient, as
appropriate for the direction of the flow.
0/U:
<patchName>
{
type waveVelocity;
// wave parameters ...
p p_rgh;
}
0/p_rgh:
<patchName>
{
type wavePressure;
}
This new pressure-velocity formulation is less stable, but generates
more accurate waveforms on patches where the velocity reverses. It is
also necessary for sub-surface cases where fixing the velocity around
the entire domain generates a continuity error.
This work was supported by Alice Gillespie, on behalf of M3 Wave
"pos" now returns 1 if the argument is greater than 0, otherwise it returns 0.
This is consistent with the common mathematical definition of the "pos" function:
https://en.wikipedia.org/wiki/Sign_(mathematics)
However the previous implementation in which 1 was also returned for a 0
argument is useful in many situations so the "pos0" has been added which returns
1 if the argument is greater or equal to 0. Additionally the "neg0" has been
added which returns 1 if if the argument is less than or equal to 0.
This addition allows for theoretical wave models to be utilised for
initialisation and as boundary conditions. Multiple models can be used
simultaneously, each with differing phases and orientations. If multiple
models are used the shapes and velocities are superimposed.
The wave models are specified in the velocity boundary condition. The
phase fraction boundary condition and the set utility both look up the
velocity condition in order to access the wave model. A velocity
boundary may be specified as follows:
inlet
{
type waveVelocity;
origin (0 0 0);
direction (1 0 0);
speed 2;
waves
(
Airy
{
length 300;
amplitude 2.5;
depth 150;
phase 0;
angle 0;
}
);
scale table ((1200 1) (1800 0));
crossScale constant 1;
}
The alpha boundary only requires the type, unless the name of the
velocity field is non-standard, in which case a "U" entry will also be
needed. The setWaves utility does not require a dictionary file; non-
standard field names can be specified as command-line arguments.
Wave models currently available are Airy (1st order) and Stokes2 (second
order). If a depth is specified, and it is not too large, then shallow
terms will be included, otherwise the models assume that the liquid is
deep.
This work was supported by Jan Kaufmann and Jan Oberhagemann at DNV GL.
