Breaking the chiral symmetry, rotation induces a secondary Hopf bifurcation in weakly nonlinear hexagon patterns which gives rise to oscillating hexagons. We study the stability of the oscillating hexagons using three coupled Ginzburg–Landau equations. Close to the bifurcation point, we derive reduced equations for the amplitude of the oscillation, coupled to the phase of the underlying hexagons. Within these equations, we identify two types of long-wave instabilities and study the ensuing dynamics using numerical simulations of the three coupled Ginzburg–Landau equations.

Peer Reviewed