Abstract:

We present experimental measurements of the velocity of a convective vortex front propagating into an unstable conductive state in a Rayleigh-Bénard system for the wide range of μ (μ"T/"Tc-1) between 4×10-4 and 2.5×10-1. The results are found to be in excellent quantitatitve agreement with the theoretical predictions following from an amplitude equation, exhibiting a sharp selection mechanism in the propagation velocity. Wave-number selection by this dynamical mechanism is also studied.