Structural and Dynamical Properties of Columnar Vortices in Rotating Rayleigh-Bénard Convection*

We study numerically the dynamical and structural properties of columnar vortices in rotating Rayleigh-Bénard convection. Our results show that the vortices form clustered structures with a characteristic length scale when their density becomes sufficiently large. Dynamically, their motion is ballistic in short time scale and crosses over to diffusive in longer time scale. We further found that the ratio of the Brownian time scale for vortex diffusion and the relaxation time scale given by the normal stress among vortices may be the key parameter that determines the structural formation of vortices.