Turbulent suppression of spinodal decomposition

Light scattering experiments reveal a strong suppression of phase separation near the critical point of a vigorously stirred binary liquid mixture. For stirring Reynolds numbers $R$ ranging from 6.0 × ${10}^3$ to 4.5 × ${10}^3$, the apparent critical temperature is depressed by ∼1 mK to ∼50 mK. This temperature depression $\Delta T_c^{\prime }$ can be fitted to a power law $\Delta T_c^{\prime }\sim R^{\lambda }$ where $\lambda \sim 2$. The magnitude of $\Delta T_c^{\prime }$ is consistent with simple models which attribute the effect to the suppression of composition fluctuations by shear; however, these models predict $\lambda \simeq 0.80$ in contrast to the observed value of ∼2. Below the apparent critical temperature the turbidity $\tau$ changes significantly throughout a temperature range of tens of millikelvin following a power law $\tau \propto {(T_c-T)}^{\zeta }$ where $\zeta$ increases from ∼1 to ∼6 as $R$ is increased.