SEMINAR
DEPARTMENT OF MECHANICAL ENGINEERING

Geophysical Flows Across Straits: A Global Dynamics Perspective

Prof. Joseph Kuehl
Dept. of Mechanical Engineering University of Delaware

Abstract

The geophysical fluid dynamics of two classes of flows across straits will be considered: 1) Gap leaping western boundary currents (relevant to the Gulf of Mexico Loop Current and South China Sea). 2) Shelf flows encountering a strait (relevant to the northeast channel of the Gulf of Maine). The importance of a “global” approach to each of these problems will be emphasized. In particular, the existence of multiple steady flow states in nonlinear fluid dynamic systems has been observed in many situations. Probably the most well- known classical fluid dynamic example is the Coanda (Teapot) Effect, in which a slowly tilted teapot will spill. In Oceanography, the discussion of multiple steady states is generally concerned with the density driven (thermohaline) overturning circulation which connects the upper and lower ocean and its climatological implications. However, in this work multiple steady states are identified as the result of a different fundamental balance than the two examples given above. In the context of a gap leaping boundary current (loop current), it is shown that the competition between inertia and vorticity constraints can lead to multiple steady states (gap leaping or gap penetrating). In the context of shelf flows across straits, it is shown that the splitting and reconnecting of inviscid streamlines can result in peculiar flow patterns similar to those observed in sea surface temperature imagery. Barotropic and baroclinic rotating table experiments and corresponding numerical computations will be presented and various properties of the system will be explored.

Biography

Joseph Kuehl is an Assistant Professor at the University of Delaware in the Mechanical Engineering Department. He holds Ph.D.s in Physical Oceanography and Mechanical Engineering from the Graduate school of Oceanography and University of Rhode (2009). His research interests include geophysical fluid dynamics (gap-leaping boundary currents, geophysical boundary layer dynamics and transport phenomena), hypersonic boundary-layer stability (numerical laminar-turbulent transition) and nonlinear vibrations (time series analysis, modal decompositiontechniquesandfinitetimeinvariantmanifoldanalysis). Hewastherecipientofthe

AFOSR Young Investigator Award (2015) for his hypersonic boundary layer stability and transition research, participates in the NATO STO ET-190 hypersonic vehicle working group and was a member of the National Academy of Science Committee on Advancing Understanding of the Gulf of Mexico Loop Current Dynamics.