Shear-flow-induced microstructural distortion of suspensions close to
the critical point is described in detail on the basis of the Smolucho
wski equation, where hydrodynamic interaction is neglected. The soluti
on of the Smoluchowski equation exhibits scaling behaviour, predicting
that the combined shear rate and correlation length dependence is cha
racterized by a single dimensionless number lambda similar to gamma xi
(4) (With gamma the shear rate and xi the correlation length of the un
sheared suspension). From the scaling relations for deformation of the
structure factor, a scaling form for the turbidity is derived. Experi
ments concerning these phenomena are presented, some of which are prel
iminary. Two types of systems are used, bath of which exhibit a gas-li
quid critical point: stearyl silica in benzene and stearyl silica in c
yclohexane with polydimethylsiloxane. Although there is an overall agr
eement with the theory, there remains a discrepancy in some of the qua
ntitative comparisons, probably due to the neglect of hydrodynamic int
eraction and the approximate nature of the closure relation that is us
ed for the three-particle correlation function.