Steady Wave‐Drift of Modeled Ice Floes

Systematic laboratory measurements are performed to determine the steady drift of isolated, tabular ice‐floe models in regular waves. A relatively simple expression for the steady wave‐induced drift of two‐dimensional floes of uniform thickness and density in deep water is developed. This empirical wave‐drift formula indicates that the drift velocity depends primarily on the ratio of wave period to ice‐floe roll period, wave steepness, and length of the floe. The highest drift velocity is produced by waves with period somewhat greater than the ice‐floe roll period, with fundamentally different drift behavior evident on either side of this maximum (long‐wave and short‐wave drift response). The dependence on wave height is found not to be linear but increases with wavelength (from approximately $H^{1/2}$ to $H^{3/2}$). A simplified equation for the roll period of a prismatic body of uniform density and rectangular cross section is developed and found to be of practical value. Floe curvature (in the vertical plane) is found to affect drift rates substantially.