DIRECT MEASUREMENT OF HYDRODYNAMIC FLUCTUATIONS IN A BINARY MIXTURE

In a binary mixture of water and ethanol, convection sets in in the form of traveling waves. Fluctuating patterns are observed below the convection threshold and interpreted as the result of thermal fluctuations. The study presented here is the first to identify these fluctuations below the convective instability, and, in particular, a recently predicted crossover in the divergence of the intensity of fluctuating traveling waves is observed for the first time. © 1995 The American Physical Society.