  2019 is the bicentenary of George Gabriel Stokes, who in 1851 described the
drag - Stokes drag - on a body moving immersed in a fluid, and 2020 is the
centenary of Christopher Robin Milne, for whom the game of poohsticks was
invented; his father A. A. Milne's "The House at Pooh Corner", in which it was
first described in print, appeared in 1928. So this is an apt moment to review
the state of the art of the fluid mechanics of a solid body in a complex fluid
flow, and one floating at the interface between two fluids in motion.
Poohsticks pertains to the latter category, when the two fluids are water and
air.
