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The effect of a shear flow on the critical behavior of a binary fluid (cyclohexane-aniline) has been investigated by light-scattering techniques. Turbidity and scattered-light-intensity measurements have been made, and the influence of all the independent parameters of the phenomenon were considered, i. e. , temperature T, shear rate S, transfer wave vector |q|, and its projection qₗ along the flow direction X. The data support the Onuki-Kawasaki (OK) description, namely, (i) an effect exists only in the region S>1, with the lifetime of concentration fluctuation. (ii) The critical temperature T₂ is lowered by the shear, so that T₂=T₂ (S) =T₂ (0) -T₀S^{₀}, with ₀=13 and =0. 630 the standard exponent of the correlation length in fluids. We find experimentally T₀= (1. 80. 2) 10^-4 and ₀=0. 530. 03, to be compared with the OK values 1. 28 10^-4 and 0. 529. (iii) The susceptibility {q} shows an anisotropy versus X, and follows a mean-field behavior versus temperature. The OK dependence {q}^_^-1vS^{₁}T-{T₂ (S) }^+BS^{₂}qₗ^+q^2 fits the data well, with ₁0. 140. 05 OK: (2-1) 3=0. 137, 1. 000. 06 (OK: =1), 0. 400. 05 (OK: 25), except for ₂, whose experimental value ₂10. 15 is about twice the OK value 8/15. Discrepancies of about a factor 2 are also found for the amplitudes A and B.
Beysens et al. (Sat,) studied this question.