Do Fish Stir the Ocean?
Jean-Luc Thiffeault, University of Wisconsin - Madison

As fish or other bodies move through a fluid, they stir theirsurroundings.  This can be beneficial to some fish, since the planktonthey eat depends on a well-stirred medium to feed on nutrients.Bacterial colonies also stir their environment, and this is even morecrucial for them since at small scales there is no turbulence to help mixing.  It has even been suggested that the total biomass in the ocean makes a significant contribution to large-scale vertical transport, but this is still a contentious issue.  We propose a simple model of the stirring action of moving bodies through both inviscid and viscous fluids.  In the dilute limit, this model can be solvedusing Einstein and Taylor's formula for diffusion (Brownian motion).

This is joint work with Steve Childress.