Gravity currents and nonlinear internal waves with trapped cores are common features in the coastal ocean. Propagating gravity currents can generate large-amplitude nonlinear internal waves, while shoaling nonlinear internal waves can develop re-circulating cores of trapped fluid. The project is a collaborative study of the dynamics of gravity currents and nonlinear internal waves with trapped cores, including parallel complementary laboratory experiments. Wave tank experiments will focus on the stages of transition between steady gravity currents and internal wave generation,and theory and experiments for waves with trapped cores. The project will investigate: what types of core circulations are possible, how they depend on the wave generation mechanism, the development of shear instabilities, how long core fluid is trapped, and the implications for long-range mass transport. Experimental results will be compared with high-resolution non-hydrostatic numerical calculations.
The results of this study could lead to substantial insights in coastal ocean circulation, mixing, and near-field river plume behavior. A major emphasis of the experimental and numerical studies is the dissemination of key results to collaborators to improve interpretation of field observations and parameterizations in regional models. As a key unknown in larval dispersal, horizontal transport by trapped cores can be of use to biologists modeling benthic population connectivity. The project will support the Ph.D. thesis work of two graduate graduate students, and involve one or more GFD fellows.
