Periodic boundary motion in thermal turbulence

A free-floating plate is introduced in a Benard convection cell with an ope n surface. It partially covers the cell and distorts the local heat flux, i nducing a coherent flow that in turn moves the plate. Remarkably, the plate can be driven to a periodic motion even under the action of a turbulent fl uid. The period of the oscillation depends on the coverage ratio, and on th e Rayleigh number of the convective system. The plate oscillatory behavior observed in this experiment may be related to a geological model, in which continents drift in a quasiperiodic fashion.