Particle motions in sheared suspensions: VIII. Singlets and doublets of fluid spheres

Abstract

The spin of single liquid spheres of carbon tetrachloride and of cyclohexanol phthalate suspended in corn syrup was measured over a range of laminar shear rates and was found to be practically identical with the value for rigid spheres. No fluid circulation inside the drops was evident until the gradient was increased sufficiently to deform the drops. The variation of drop deformation with initial diameter and velocity gradient agreed with Taylor's theory. The standard and head-on collision doublets of equal-sized liquid spheres behaved similarly to those of rigid spheres. The angular velocity of standard doublets showed a slight deviation from the equation for rigid prolate spheroids of axis ratio 2, presumably because of slight deformation of each drop. Standard collisions resulted in coalescence only when sufficient contact time was allowed for film drainage and only in freshly prepared corn syrup suspensions. Head-on collisions almost always resulted in coalescence, although the time required increased with age of the suspension. When glycerine was used as the medium, there was no aging effect. It is concluded that the inhibition of internal circulation and of coalescence in the corn syrup suspensions was due to the formation of a viscoelastic interfacial film.