Abstract: Rayleigh Bénard(RB) convective system is simulated numerically using Direct Simulation Monte Carlo (DSMC) method which origins from micro-molecular dynamics. On the basis of DSMC simulation results, the critical Rayleigh number is obtained, which is consistent with the linear stability theory. The double periods bifurcate route to chaos in RB system is obtained by spectrum analysis of temperature signal on the center point of RB system; At the same time, the nonlinear characteristics such as conjunction dimensionality and Lyapunov index are obtained by modern chaotic analysis method.

Key words: DSMC method, Rayleigh Bénard system, chaos, bifurcation, nonlinear analysis