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BATHYMETRIC IRREGULARITIES, JET FORMATION, AND SUBSEQUENT MIXING PROCESSES
Citation:
Frick, W E., S. Emerman, AND A C. Sigleo. BATHYMETRIC IRREGULARITIES, JET FORMATION, AND SUBSEQUENT MIXING PROCESSES. Presented at American Geophysical Union Ocean Sciences Meeting, San Antonio, TX, January 24-29, 2000.
Description:
It is well known that bathymetric contours influence and steer currents and that irregularities in bathymetry contribute to the formation of aquatic non-buoyant jets and buoyant plumes. For example, bathymetric irregularities can channel flow through canyons or accelerate flow over ridges to produce regions of increased kinetic energy density, which is what jets and plumes are, in addition to the latter being buoyant. Considering sufficiently large scales, upon reaching uniform bathymetry, these flows will inevitably mix with ambient fluid. While this mixing effect is well known, and is sometimes called entrainment, the underlying mechanism remains relatively obscure and esoteric. An application of a novel theory for turbulence places an understanding of the basic mixing process within the reach of all researchers and provides a model for turbulent flow that may prove useful for parameterizing turbulence quantitatively in many hydrodynamical models. The basic thesis of the model is that shear between the ambient fluid and the jet helps to transform one-dimensional flow into divergent multi-dimensional flow. Subsequently, the elevated momentum in the jet is available to expand the fluid in the divergent flow region. The main manifestation of this compressible process is not a significant difference in density (however, it is shown that, the pressure gradient term in the so-called incompressible Bernoulli equation is a compressible term) but a reduction in pressure causing the inflow, or entrainment or mixing, of ambient fluid into the jet.