Light-scattering study of a turbulent critical binary mixture near the critical point

We have measured the angular distribution of light scattered from two critical binary mixtures which are being continuously and turbulently stirred at a fixed temperature T close to the critical point. At temperatures above Tc, it is observed that the structure factor S(k) is strongly modified at small k values. S(k) exhibits a scaling form over a range of temperatures which span the critical temperature of the unstirred system. This functional form, however, changes as the stirring rate is varied. The present experimental results are consistent with earlier turbidity measurements, but the angular distribution data show no evidence of a well-defined transition from the ordered to disordered state as the temperature is decreased. Our results will be compared with a theory of Onuki [Phys. Lett. 101A, 286 (1984)].