Coherent structures in turbulent convection, an experimental study

We present results from a visualization experiment in Rayleigh-Bénard convection in water at high Rayleigh number. We distinguish three kinds of coherent structures in the flow: waves along the boundary layers, plumes, and spiraling swirls. The waves originate from the interaction of plumes with the boundary layers. The spiraling swirls appear to be the result of a shear instability of the viscous boundary layer. We describe the “life cycle” of these structures in the cell, and when we focus on the waves and characterize them quantitatively using local temperature measurements.