Numerical and experimental investigation of extreme events in JONSWAP seas

The dynamics of nonlinear water waves and extreme waves in particular can be accurately investigated numerically using a numerical wave tank (NWT), implemented by the higher-order spectral method (HOS). In fact, a number of laboratory studies validated the proposed numerical approach, while a very high validation accuracy is reached. We present a numerical study based on a HOS-NWT scheme in the investigation of the one-dimensional propagation of extreme events in JONSWAP seas, having their origin from exact breather solutions of the nonlinear Schrödinger equation. Indeed, breathers are known to model extreme waves, when the wave field's spectrum is assumed to be narrow-banded. On the other hand recent experimental studies confirmed that these localized structures can also evolve, when wind or significant perturbations are at play. We will investigate the validity of the proposed numerical scheme by comparing the simulation results to laboratory data. The dynamics of both wave fields show indeed a very good agreement.