Do Fish Stir the Ocean?
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
This is joint work with Steve Childress.