Excitation of an extreme wave by standing current

Abstract

The statistics suggest that extreme waves cause more damage in shallow waters and at the coast than in the deep sea. In the linear theory of the formation of extreme waves, their existence is interpreted as a local superposition of surface monochromatic waves. The event of excitation of extreme waves can be understood as an increase in natural oscillations of the water basin. The conditions for the excitation and sustaining of natural oscillations are the proximity of the periods of exciting traveling waves to the period of traveling waves and the speed of movement of the exciting current to the phase speed of propagation of traveling waves of the reservoir. Examples of stimulating natural oscillations are presented. We determined the range of expected periods of natural oscillations, which range from 30 seconds to 24 hours. Synchronously and in common-mode with the oscillations of standing waves between their antinodes, a "standing" current occurs with a measured speed of up to 11 km/h. We presented a hypothesis about the possibility of stimulating natural oscillations of water bodies by a standing current, which changes its direction due to the movement of the water surface from the trough of the wave to its crest, and back. A model of stimulating oscillations by the waves with a constant period and currents with constant and variable speeds has been developed.