Some new routes to chaos in Rayleigh-Benard convection

Abstract

For Rayleigh-Benard convection in a cylindrical container of radius-to-height ratio 2.93 and Prandtl number between 0.49 and 0.78, we report new sequences of transitions from steady to time-dependent flow. Oscillations of period comparable to the horizontal thermal diffusion time $t_h$ and transients of many $t_h$ in duration have been observed. The dependence of these transitions on Prandtl number is consistent with predictions for the skewed-varicose instability.