Critical Phenomena of Classical Fluids under Flow. I: Mean Field Approximation

We investigate steady states properties of critical, classical fluids subjected to incompressible flows in this and subsequent papers. Critical fluctuations can be greatly affected by flows when magnitudes of velocity gradients, which have the dimension of frequency, exceed the average decay rate of critical fluctuations. There, various interesting nonlinear effects can be expected and will be observed in experiments. This is analogous to polymeric solutions with flow. The first paper is concerned with some general discussion of the variance of order parameter fluctuations in the mean field approximation.