TIME AND LENGTH SCALES IN ROTATING RAYLEIGH-BENARD CONVECTION

We report experimental results for Rayleigh-Bénard convection of a fluid (CO2) in a cylindrical cell with radius-to-height ratio 40 and rotated about a vertical axis. Near the critical rotation frequency for the Küppers-Lortz instability and for small εΔT/ΔTc-1, we measured the frequency ωa and the correlation length ξ of the pattern dynamics. They could be fit by power laws in ε only when exponent values much smaller than those predicted from amplitude equations were used. Alternately, the predicted exponents could be retained if the threshold were shifted to negative values of ε, thus yielding finite ωa and ξ at onset. © 1995 The American Physical Society.