Whirling hexagons and defect chaos in hexagonal non-Boussinesq convection

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.