PARTICLE SIMULATION OF 3-DIMENSIONAL CONVECTION PATTERNS IN A RAYLEIGH-BENARD SYSTEM

The transition of convection patterns in the three-dimensional Rayleig h-Benard system is simulated using the direct simulation Monte Carlo m ethod. The simulation region is a rectangular box with an aspect ratio of 8:8:1, and the number of simulation particles is 2.048 x 10(7). A hexagonal Bow pattern is observed in the convection state with the Ray leigh number slightly higher than the critical value. It is found that the hexagonal flow pattern evolves into a roll pattern with an increa se in the Rayleigh number. A hysteresis is seen in the transition betw een the hexagonal and mil patterns.