Long internal waves in shear flows: topographic resonance and wave-induced global instability

Issues pertaining to a mechanism whereby long internal waves in shallow seas may give rise to enhanced rates of resuspension of sedimentary material are addressed. The proposed mechanism is intimately related to the creation of conditions in the bottom boundary layer which are favorable for how separation and spontaneous onset of global instability. It is shown that long waves generated by topographic resonance and propagating upstream against the oncoming current, especially a sheared current, have a strong tendency to release a coherent, pulsating dynamics in their footprint. The passage-through-resonance problem For a sheared, stratified Row is considered, conditions for topographic resonance in the Row model are defined, and preliminary results for the unsteady dynamics in the boundary layer under the footprint of a long wave packet are presented. (C) 2001 Elsevier Science B.V. All rights reserved.