Abstract
Recent observations have shown that islands and constrictions may be the sites of significant internal wave activity in sea straits. In this paper we examine one generation mechanism: resonant forcing by transcritical flow past topography. Experiments were conducted on the large rotating platform at the Coriolis Laboratory, Institut de Mécanique de Grenoble, Grenoble, France. A slender body was towed through a two‐layer stratified rotating channel, simulating the flow past an island or constriction in a strait. For a range of Froude numbers, blockage coefficients, and rotation rates, nonlinear internal Kelvin waves were generated upstream. The dependence of the wave parameters on the Froude number, Rossby number, and blockage coefficient was measured. The transition between subcritical and supercritical flow is found to occur at Froude numbers greater than unity, to depend on the blockage, but to be essentially independent of the internal Rossby radius of deformation. The results are compared with recent similar measurements of single‐layer flows in nonrotating channels, and good agreement is obtained. The nonlinear Kelvin waves which are generated upstream are found to be similar in all respects to those described by Renouard et al. (1987).
Published Version
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