This model builds up phase fraction and velocity fields from multiple
first-order waves, sampled from a selectable wave spectrum.
Usage:
Property | Description | Required? | Default
----------+-------------------------------+-----------+-------------
depth | The water depth [m] | no | great
spectrum | The wave spectrum | yes |
n | The number of times to sample | yes |
| the spectrum | |
span | The fractional range across | no | (0.01 0.99)
| which to sample the spectrum | |
setFormat | The format with which to plot | no | none
| the spectrum | |
Example specification in constant/waveProperties:
waves
(
irregular
{
spectrum PiersonMoskowitz; // or JONSWAP
PiersonMoskowitzCoeffs
{
U19_5 15;
}
JONSWAPCoeffs
{
U10 10;
F 200e3;
}
n 16;
span (0.01 0.99);
}
);
Stokes-type waves (i.e., Airy, Stokes2 and Stokes5) now support
specification in terms of wave period, as well as length. The following
specifications are therefore equivalent:
Stokes2
{
length 300; // <-- Wave length specified
amplitude 2.5;
phase 0;
angle 0;
depth 50;
}
Stokes2
{
period 15.643; // <-- Wave period specified
amplitude 2.5;
phase 0;
angle 0;
depth 50;
}
Note that the period is that of the wave in a reference frame with zero
mean flow. Specifying a doppler shifted period is not yet supported.
Exactly one of period or length must be specified. If both, or neither,
are provided then an error will be generated.
Corrections have also been made to the calculation of the celerity of
Stokes2 and Stokes5 waves.
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.
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.
