ON THE INFLUENCE OF AN ISOLATED SUBMERGED OBSTACLE ON A BAROTROPIC TIDAL FLOW

The influence of an isolated submerged obstacle on the dynamics of a m aterial particle is studied within the limits of a barotropic, quasi-g eostrophic model of oceanic S-plane flow, for cases in which the incid ent how has both steady and tidal components of velocity. Two kinds of motion are shown to occur, namely (i) the particle performs quasi-per iodic oscillations in the vicinity of the obstacle or (ii) the particl e acquires an infinite character (i.e., the particle leaving the vicin ity of the obstacle is irrevocably advected downstream by the backgrou nd flow). Sufficient conditions are obtained for the existence of both classes of motion. Conditions for domain alternation of the finite an d infinite solutions have been derived numerically for different exter nal parameters (e.g., the kinematic characteristics of the flow field and the height of topography). Using the Contour Dynamics Method, resu lts are presented to show how the predicted motions of individual part icles can be extended to predict the behaviour of finite water volumes in general and particle admixture patches in particular.