Rotating convection in an anisotropic system

We study the stability of patterns arising in rotating convection in weakly anisotropic systems using a modified Swift-Hohenberg equation. The anisotropy, either an endogenous characteristic of the system or induced by external forcing, can stabilize periodic rolls in the Küppers-Lortz chaotic regime. We apply this to the particular case of rotating convection with time-modulated rotation where recently, in experiment, spiral and target patterns have been observed in otherwise Küppers-Lortz-unstable regimes. We show how the underlying base flow breaks the isotropy, thereby affecting the linear growth rate of convection rolls in such a way as to stabilize spirals and targets. Throughout we compare analytical results to numerical simulations of the Swift-Hohenberg equation.