 |
| Titel |
Wave kinematics of random directional seas |
| VerfasserIn |
Alberto Alberello, Amin Chabchoub, Miguel Onorato, Alexander Babanin, Alessandro Toffoli |
| Konferenz |
EGU General Assembly 2014
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250086659
|
| Publikation (Nr.) |
 EGU/EGU2014-569.pdf |
|
|
|
|
|
| Zusammenfassung |
| The inclusion of at least the second order effects is considered necessary to obtain an
accurately representation of ocean waves. While this is true for the surface elevation, very
little is known concerning the velocity potential and hence the kinematics of the wave field.
Here we attempt to investigate the role of second and higher order nonlinearity on the
velocity. Particular emphasis is given to the effect of the wave directional spreading on
nonlinear wave-wave interaction.
The second order, which represents the most obvious effect of nonlinearity in the ocean, have
been computed with a perturbation method that gives the exact solution of the boundary value
problem. An Higher Order Spectral Method (HOSM), which takes into account nonlinear
wave dynamics and hence modulational instability processes that are regarded as being
responsible for the generation of extreme waves is used to compute both water elevation and
velocity potential too. Different initial random directional seas have been considered and
Monte Carlo simulations have been performed to study the statistical properties of wave
kinematics.
Results show that the statistical properties of the wave kinematics is significantly
affected by the wave directional spreading. Departure of the tail of the probability
distribution from Gaussian statistics already starts at second order and are further
amplified by higher order nonlinear effects. The increase of the orbital velocity under
a trough is mainly an effect of the second order contribution, the growth of the
crest velocity is mainly due to a third order effect. Nevertheless the directionality
of the wave field, together with the water depth, can strongly affect the relative
importance of second, third and higher order contribution on the wave kinematic. |
|
|
|
|
|
|