Extreme Waves and Modulational INSTABILITY IN TWO HORIZONTAL DIMENSIONS
| Project acronym: | HyIII-NTNU-4 |
| Name of Group Leader: | MIGUEL ONORATO, Universita di Torino, Dipartimento di Fisica Generale, Torino, Italy. onorato@ph.unito.it Jaak Monbaliu, Katholieke Universiteit Leuven - Hydraulics Laboratory – Department of Civil Engineering, Belgium. jaak.monbaliu@bwk.kuleuven.be |
| User-Project Title: | Extreme Waves and Modulational INSTABILITY IN TWO HORIZONTAL DIMENSIONS |
| Facility: | Ocean Basin |
| Proceedings TA Project: | Statistical properties of mechanically generated surface gravity waves: a laboratory experiment in a 3d wave basin |
| Data Management Report: | Data Management Reports Page You will need to login to view this page |
Summary:
The goal of the present research was to investigate the role of modulational instability (or Benjamin-Feir instability) on the formation of freak waves in 2 horizontal dimensions. In the last few years there has been quite a lot of effort in trying to understand what are the causes of formation of extreme waves. Apart from the linear wave superposition and the effects of currents in waves (caustic theory), the modulational instability has been found to be a relevant mechanism for the formation of extreme waves in long crested sea states conditions. This result has been supported by numerical, theoretical and experimental work.
A recent important discovery on extreme waves concerns their formation in conditions of crossing seas. The aforementioned discovery, of major relevance for applicative purposes, have never been tested in a wave tank facility and should be considered as a major result to achieve. We intended therefore to perform experimental tests in crossing sea states.
The most important result so far consists in the fact that the probability density function of wave crests and wave heights depends strongly on the directional energy distribution of the waves. We were able to estimate the probability density function of the surface elevation from experimental data for different degrees of directionality and wave steepness. The results have big impact on the field because they can be directly used for forecasting extreme events.
The results will be fundamental for developing an operational model for extreme wave forecasting.
| Publication References |
| Statistical properties of directional surface gravity waves: A laboratory experiment with mechanically generated waves; European Geophysical Union, Vienna, Austria, 13 – 18 April 2008 Gramstad, O.; Cavaleri, L.; Janssen, P.; Monbaliu, J.; Onorato, M.; Osborne, A.R.; Serio, M.; Stansberg, C.T.; Toffoli, A.; Trulsen, K. |
| Statistical properties of mechanically generated surface gravity waves: a laboratory experiment in a 3D wave basin, WAVES IN SHALLOW WATER ENVIRONMENT, Helsinky, Finland, 1-5 June, 2008 Onorato, Miguel ; Cavaleri, Luigi ; Gramstad, Odin ; Janssen, Peter A.E.M. ; Monbaliu, Jaak ; Osborne, Al R. ; Stansberg, Carl-Trygve ; Toffoli, Alessandro & Trulsen, Karsten |
| Statistical properties of mechanically generated surface gravity waves: a laboratory experiment in a 3D wave basin, ROGUE WAVES 2008, Brest France, 13-15 October, 2008 Onorato, Miguel ; Cavaleri, Luigi ; Gramstad, Odin ; Janssen, Peter A.E.M. ; Monbaliu, Jaak ; Osborne, Al R. ; Stansberg, Carl-Trygve ; Toffoli, Alessandro & Trulsen, Karsten |
| Statistical properties of mechanically generated surface gravity waves: a laboratory experiment in a 3D wave basin M. Onorato, L. Cavaleri, S. Fouques, O. Gramstad, P.A.E.M. Janssen, J. Monbaliu, A.R. Osborne, C. Pakozdi, M. Serio, C.T. Stansberg A. Toffoli, K.Trulsen, submitted to Journal of Fluid Mechanics 2008 |