NONEQUILIBRIUM FLUCTUATIONS IN LIQUID-MIXTURES UNDER THE INFLUENCE OF GRAVITY
 
                                                                       SEGRE PN, SENGERS JV
                                                                                 PHYSICA A
                                                                     198: (1-2) 46-77 SEP 1 1993
 
                                                                            Abstract:
The theory of fluctuations in liquid mixtures that are subjected to a stationary temperature gradient, while still
being kept in a quiescent state, is extended to include the influence of gravity. Specifically, we evaluate the effects
of a temperature gradient combined with gravity on the Rayleigh component of the light-scattering spectrum of
liquid mixtures. For the case that the liquid system is heated from below we analyze the crossover from
one-component-like to mixture-like behavior of the critical slowing down of the fluctuations near the convective
instability. When the liquid mixture is heated from above, propagating modes appear for sufficiently large
temperature gradients; a phenomenon similar to that previously encountered in one-component liquids. By
retaining all the couplings between the temperature and concentration fluctuations in the hydrodynamic equations,
we have also derived a new expression for the Rayleigh number R in liquid mixtures.