Yuan-Nan Young, Hermann Riecke and Werner Pesch

New J. Physics 5 (2003) 135, Movies

We study hexagon patterns in non-Boussinesq convection of a thin rotating layer of water. For realistic parameters and boundary conditions we identify various linear instabilities of the pattern. We focus on the dynamics arising from an oscillatory side-band instability that leads to a spatially disordered chaotic state characterized by oscillating (whirling) hexagons. Using triangulation we obtain the distribution functions for the number of pentagonal and heptagonal convection cells. In contrast to the results found for defect chaos in the complex Ginzburg-Landau equation, in inclined-layer convection, and in spiral-defect chaos, the distribution functions can show deviations from a squared Poisson distribution that suggest non-trivial correlations between the defects.

Movie of pattern evolution with periodic boundary conditions
Movie of pattern evolution in circular container

Stability limits of steady hexagons

Snapshot of convection pattern

Triangulation and identification of heptagons and pentagons