Hydrodynamic Theory of Light Scattering from a Fluid in a Nonequilibrium Steady State

Two new features, finite-size effects and a new hydrodynamic eigenvalue problem, are essential for a consistent discussion of the scattering of light by a fluid in a non-equilibrium steady state. The light-scattering structure factor is computed for the case of a steady thermal gradient and a steady shear flow in a fluid. The height differences found in the Brillouin peaks differ from those obtained by Ronis, Procaccia, and Oppenheim and Machta, Oppenheim, and Procaccia.