What does the Gulf of Mexico have in common with a teapot?

RLM 11.204
Joe Kuehl
National Center for Hypersonic Research, Texas A&M University
What does the Gulf of Mexico have in common with a teapot?

The best known fluid system exhibiting multiple steady flow states is the Coanda (Teapot) Effect, in which a slowly tilted teapot will spill. In oceanography, discussions of multiple steady states generally concern density-driven overturning circulation, which connects the upper and lower ocean; this phenomenon has climatological implications.  In the present work multiple steady states are the result of a different fundamental balance from the two examples given above.  We examine a gap-leaping boundary current (a loop current) and  show that the competition between inertia and vorticity constraints can lead to two solutions, a gap-leaping or gap-penetrating current. We present rotating table fluid experiments that exhibit a hysteretic transition between the two states. The system is well described by a cusp catastrophe geometry of solutions.  The experiments agree with results we obtain from numerics and theory.  The cusp solutions provide insight into geophysical fluid dynamic systems such as loop currents.