The onset of chaotic convection in large-Prandtl-number fluids has been found to occur in the form of elongated cells with aperiodic boundary-layer instabilities. The dynamics of this phenomenon has been monitored in the physical domain, and also in the spectral and phase spaces. In order to describe more precisely the underlying mechanisms of chaotic thermal convection, we find it useful to introduce the notion of ‘‘thermal attractor’’ in the physical domain and to conduct a systematic study of the evolution of the spectral energy surfaces. We propose here a relationship between this thermal attractor and the presence of a strange attractor in the phase space.

• Received 14 September 1987

DOI:https://doi.org/10.1103/PhysRevA.38.328