P. Boccotti

Bio: P. Boccotti is an academic researcher. The author has contributed to research in topics: Wind wave model & Wave flume. The author has an hindex of 1, co-authored 1 publications receiving 311 citations.

Wave Mechanics for Ocean Engineering

Abstract: Periodic Wave Pattern - the approach of differential calculus Periodic Wave Pattern - the control volume approach Wave Effects on Coasts Wind Generated Waves - basic concepts Analysis of the Sea States - the time domain The Wave Climate Design Waves and Risk Analysis Analysis of the Sea States in the Space-Time The Theory of Quasi-Determinism Uses and Consequences of the Quasi-Determinism Theory Analysis of the Wave Forces on Offshore Structures Calculation of the Wave Forces on Offshore Structures Stability Analysis of Coastal Structures Topics Calling for an Overall Overview of Offshore and Coastal Engineering.

Real world ocean rogue waves explained without the modulational instability

Abstract: Since the 1990s, the modulational instability has commonly been used to explain the occurrence of rogue waves that appear from nowhere in the open ocean. However, the importance of this instability in the context of ocean waves is not well established. This mechanism has been successfully studied in laboratory experiments and in mathematical studies, but there is no consensus on what actually takes place in the ocean. In this work, we question the oceanic relevance of this paradigm. In particular, we analyze several sets of field data in various European locations with various tools, and find that the main generation mechanism for rogue waves is the constructive interference of elementary waves enhanced by second-order bound nonlinearities and not the modulational instability. This implies that rogue waves are likely to be rare occurrences of weakly nonlinear random seas.

On nonlinear wave groups and crest statistics

Abstract: We present a second-order stochastic model of weakly nonlinear waves and develop theoretical expressions for the expected shape of large surface displacements. The model also leads to an exact theoretical expression for the statistical distribution of large wave crests in a form that generalizes the Tayfun distribution (Tayfun, J. Geophys. Res., vol. 85, 1980, p. 1548). The generalized distribution depends on a steepness parameter given by μ = λ3/3, where λ3 represents the skewness coefficient of surface displacements. It converges to the Tayfun distribution in narrowband waves, where both distributions describe the crests of all waves well. In broadband waves, the generalized distribution represents the crests of large waves just as well whereas the Tayfun distribution appears as an upper bound and tends to overestimate them. However, the theoretical nature of the generalized distribution presents practical difficulties in oceanic applications. We circumvent these by adopting an appropriate approximation for the steepness parameter. Comparisons with wind-wave measurements from the North Sea suggest that this approximation allows both distributions to assume an identical form with which we can describe the distribution of large wave crests fairly accurately. The same comparisons also show that third-order nonlinear effects do not appear to have any discernable effect on the statistics of large surface displacements or wave crests.