WAVES DUE TO A STEADILY MOVING SOURCE ON A FLOATING ICE PLATE. PART 2.

This paper extends previous theoretical work on waves in floating ice plates to take account of the following effects: (1) compressive stress in the plane of the plate, (ii) uniform flow in the underlying water, and (iii) stratification of the underlying water. The first two effects are unlikely to be important in practice, causing respectively a slight decrease in phase speed and mainly a re-orientation of the wave pattern due to a steadily moving source. A two-layer model is used to describe stratification, which introduces a new system of slow internal waves associated with the layer interface, while the surface flexural waves are only slightly modified. In the case of unstratified water there is a minimum speed C//m//i//n such that more slowly moving sources excite a static rather than a wavelike response in the ice. With stratified water there remains a variety of steady wave patterns due to the internal waves, at source speeds below C//m//i//n. Another important effect of stratification is to greatly increase wave drag. For certain source load distributions, internal-wave amplitudes may grow until linear theory is no longer applicable.