RESONANCE INTERACTIONS OF WAVES IN AN ICE CHANNEL

The properties of low-amplitude surface waves propagating in an ice ch annel are investigated in the shallow-water approximation. The ice cov er is modelled either by a rigid cap or by a thin elastic plate floati ng on a liquid surface. It is shown that an ice channel is a waveguide for surface waves. The dispersive properties of the natural oscillati ons of the liquid in the channel are investigated. The resonance veloc ities of the motion of the load on the channel surface, at which the a mplitude of the forced oscillations of the liquid increases without li mit in time, are determined. The decay instability of the natural osci llations of high harmonics with respect to waves of the first mode is demonstrated. The process is described by the standard equations for n on-linear three-wave interaction. The investigations lead to the concl usion that critical modes of motion of a boat are realizable in an ice channel. (C) 1998 Elsevier Science Ltd. All rights reserved.