MC Study of Effects of Shear on the Phase Transition of Binary Mixtures

Abstract

It is well known that systems near critical points can be brought into a state far from equilibrium by a relatively small disturbance. A good example is a critical binary mixture under shear flow /1/. Experiments and theories have shown that the critical properties of the system can be drastically changed when critical fluctuations are exposed to shear. In 1979 Beysens et al. /2/ found that critical fluctuations were strongly suppressed by a shear flow together with a lowered critical temperature T _c . Their findings were supported by the theories of Onuki et al. /3/. However, very recently, Cates et al. /5/ have shown that even when the concentration fluctuations are suppressed by the shear flow, the T _c of an isotropic-to-lamellar transition of a liquid crystal can still be raised. The main difference of the model of Onuki et al. and that of Cates et al. is that velocity fluctuations are neglected in the latter model. It is pointed out to the author by Onuki /5/ that it is the velocity fluctuations and its coupling to the composition fluctuations which lowers T _c .