The excitation of rogue waves in a variable medium: an experimental study on the interaction of water waves and currents

A. Toffoli, T. Waseda, H. Houtani, T. Kinoshita, K. Collins, D. Proment, M. Onorato

Published 2013-03-28Version 1

We show experimentally that a stable wave propagating into a region characterized by an opposite current may become modulationaly unstable. Experiments have been performed in two independent wave tank facilities; both of them are equipped with a wavemaker and a pump for generating a current propagating in the opposite direction with respect to the waves. The experimental results support a recent conjecture based on a current-modified Nonlinear Schr\"odinger equation which establishes that rogue waves can be triggered by non-homogeneous current characterized by a negative horizontal velocity gradient.