Numerical Simulation Of Rogue Waves In Deep Water Considering Wave/Current Interaction

Rogue waves are exceptionally tall and abnormally shaped waves in the real sea state. It can cause grievous damage to the structure of offshore engineering. Due to its lack of recorded data, complex mechanism, until now it is still a hard work to establish the numerical model that can describe the rogue waves very well. So the generation of rogue waves in the laboratory is rather eagerly needed. The numerical study in this paper is supposed to contribute to the experimental study, so the methods that can be applied to generate the rogue waves in the laboratory are paid attention on. And the mechanism of the generation of rogue wave and its physical characteristics are investigated in this paper.The main contents in this paper include:1) A spatial domain model of fourth-order modified nonlinear Schr(?)dinger(mNLS) equations in one horizontal dimension (1D) was established for describing the deep-water wave trains in a prescribed stationary current field; 2) The transient water waves (TWW) was adopted as the initial condition of the mNLS equations to simulate the generation of rogue wave. The influence of nonlinearity on concentration time/place, wave height, inclination and particle velocity are shown; 3) Current modified nonlinear Schr(?)dinger (NLSC) equations are established to investigate the influence of interaction between wave and current on the propagation of rogue wave; At the same time, the probability of the occurrence of wave breaking is discussed;4) The targeted rogue waves with and without currents in the real sea state are simulated through the optimization of the initial phase of irregular waves.The following conclusions are drawn in this paper:1) In nonlinear wave evolution, the shape of free surface at the concentration location is asymmetric in time with and without currents, which is different from the linear evolution; 2) Currents affect the shape of wave significantly. The asymmetry of focusing wave in time series is intensified when current coexists; 3) Concentration location is shifted forward on counter current while backward on co-current. But the existence of the current doesn't change the focusing time very much; 4) Targeted rogue wave with high accuracy is successfully generated through controlling the initial phase of irregular wave using optimization methods of genetic algorithm and sequential quadratic program.