Rogue wave

About: Rogue wave is a research topic. Over the lifetime, 2977 publications have been published within this topic receiving 70933 citations. The topic is also known as: freak wave & monster wave.

Coherence and predictability of extreme events in irregular waves

Abstract: . This paper concerns the description and the predictability of a freak event when at a certain position information in the form of a time signal is given. The prediction will use the phase information for an estimate of the position and time of the occurrence of a large wave, and to predict the measure of phase coherence at the estimated focussing position. The coherence and the spectrum will determine an estimate for the amplitude. After adjusting for second order nonlinear effects, together this then provides an estimate of the form of a possible freak wave in the time signal, which will be described by a pseudo-maximal signal. In the exceptional case of a fully coherent signal, it can be described well by a so-called maximal signal. We give four cases of freak waves for which we compare results of predictions with available measured (and simulated) results by nonlinear AB-equation (van Groesen and Andonowati, 2007; van Groesen et al., 2010). The first case deals with dispersive focussing, for which all phases are (designed to be) very coherent at position and time of focussing; this wave is nearly a maximal wave. The second case is the Draupner wave, for which the signal turns out to be recorded very close to its maximal wave height. It is less coherent but can be described in a good approximation as a pseudo-maximal wave. The last two cases are irregular waves which were measured at MARIN (Maritime Research Institute Netherlands); in a time trace of more than 1000 waves freak-like waves appeared "accidentally". Although the highest wave is less coherent than the other two cases, this maximal crest can still be approximated by a pseudo-maximal wave.

High power pulses extracted from the Peregrine rogue wave

Abstract: We address various initial excitations of the Peregrine rogue wave and establish a robust transmission scheme of high power pulses extracted from the Peregrine rogue wave in a standard telecommunications fiber. The results show that the Peregrine rogue wave can be excited by using a weak pulse atop a continuous wave background and that the high power pulses extracted from the Peregrine rogue wave exhibit the typical characteristics of breathing solitons. The influence of higher-order effects, such as the third-order dispersion, the self-steepening and the Raman effect, on the propagation of the pulse extracted from the peak position and the interaction between neighboring high power pulses induced by initial perturbations are also investigated.

Controllable parabolic-cylinder optical rogue wave.

Abstract: We demonstrate controllable parabolic-cylinder optical rogue waves in certain inhomogeneous media. An analytical rogue wave solution of the generalized nonlinear Schrodinger equation with spatially modulated coefficients and an external potential in the form of modulated quadratic potential is obtained by the similarity transformation. Numerical simulations are performed for comparison with the analytical solutions and to confirm the stability of the rogue wave solution obtained. These optical rogue waves are built by the products of parabolic-cylinder functions and the basic rogue wave solution of the standard nonlinear Schrodinger equation. Such rogue waves may appear in different forms, as the hump and paw profiles.

Influence of Nonlinear Irregular Waves on the Fatigue Loads of an Offshore Wind Turbine

Abstract: In order to make offshore wind power a cost effective solution that can compete with the traditional fossil energy sources, cost reductions on the expensive offshore support structures are required. One way to achieve this, is to reduce the uncertainty in wave load calculations by using a more advanced model for wave kinematics. As offshore wind turbines are generally sited in shallow water, nonlinear effects which results in steeper waves with higher velocities and accelerations are common. Whereas extreme waves are modeled with higher-order nonlinear regular wave models, fatigue loads are calculated from kinematics obtained by a low-fidelity linear irregular wave model. In this paper, a second-order wave model that is employed to simulate the dynamic response due to nonlinear irregular waves on a full set of IEC-standard load cases. This method is computationally efficient, which is particularly useful for design optimization studies. It is shown that by using this method for a 25 m deep site in the German Bight, equivalent fatigue loads increase by 7.5 % compared to the traditional linear wave model. The effect of nonlinear waves on fatigue is most prevalent in the foundation and tower parts near the sea surface. Furthermore, it is found that the increase in fatigue damage accumulation is most prevalent in wind-wave misaligned load cases, in which aerodynamic damping is absent.

Boundary Perturbation Methods for Water Waves

Abstract: The most successful equations for the modeling of ocean wave phenomena are the free–surface Euler equations. Their solutions accurately approximate a wide range of physical problems from open–ocean transport of pollutants, to the forces exerted upon oil platforms by rogue waves, to shoaling and breaking of waves in nearshore regions. These equations provide numerous challenges for theoreticians and practitioners alike as they couple the difficulties of a free boundary problem with the subtle balancing of nonlinearity and dispersion in the absence of dissipation. In this paper we give an overview of, what we term, “Boundary Perturbation” methods for the analysis and numerical simulation of this “water wave problem”. Due to our own research interests this review is focused upon the numerical simulation of traveling water waves, however, the extensive literature on the initial value problem and additional theoretical developments are also briefly discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)