Nonlinear Rayleigh–Bénard convection with square planform

Abstract

Fully three-dimensional numerical solutions are presented for Rayleigh-Bénard convection subject to stress-free boundary conditions. A motion with square planform is studied for varying Rayleigh number R and Prandtl number σ. It may be understood partly in terms of a truncated modal representation (after Lorenz 1963). Thermal layers of unusual structure are found at high R. For small σ, steady solutions exist, but are not of ‘flywheel’ type, and the heat transport depends strongly on σ. The study also verifies that laminar convective flows may be ergodic.