Numerical evidence for coexistence of roll and square patterns in Rayleigh-Benard convection

The three-dimensional Rayleigh-Benard convection is simulated numerically using the lattice Boltzmann method. The Rayleigh number and the Prandtl number are fixed at 5805 and 0.71, respectively. Stable or oscillatory roll patterns with different wave number and Nusselt number are observed in the steady state. It is found that the stable asymmetric square patterns are realized under the same condition for the stable or oscillatory roll patterns. It is suggested that the coexistence of roll and square patterns would be established under controlled initial conditions. (C) 2003 Elsevier B.V. All rights reserved.