Component Wave Interactions and Irregular Wave Kinematics

Abstract

The kinematics of an irregular wave is characteristically different from that of a regular wave with similar wave height and frequency in two respects. First, an irregular wave induces larger particle velocities near the surface and smaller velocities at greater depths than that for a regular wave. Secondly, its horizontal velocity under a trough is larger than that under an adjacent crest at the same depth while the corresponding difference in regular waves is insignificant. To understand the mechanism of these kinematic characterisitcs unique to irregular waves, the kinematics of a shorter wavelength wave riding on a longer wavelength wave (a dual‐component wave) is investigated numerically and experimentally. The effects of the interaction between short and long waves on the kinematics of a dual‐component wave are analyzed, and the results indicate that the kinematic characteristics of irregular waves are due mainly to the component wave interaction. Hence, the effects of component wave interaction must be appropriately considered for the accurate prediction of the kinematics in an irregular wave field.