Experimental determination of drop shape in slow steady shear flow

Theoretical predictions for the 3D shape of a Newtonian drop immersed in a Newtonian fluid under slow dow have been available for a long time (C.E. Ch affey and H. Brenner, J. Colloid Interface Sci. 24, 258 (1967); J.M. Rallis on, J. Fluid Mech. 98, 625 (1980)). The predictions contain four scalar coe fficients, given in terms of the viscosity ratio of the component fluids. I n this work, experimental values of such coefficients were measured for the case of two Newtonian fluids in simple shear how. The experiments were car ried out in a parallel plate apparatus, equipped with video-enhanced micros copy, and the measurements were performed by image analysis techniques. The results were also compared to theoretical calculations and provide the fir st complete assessment of shape predictions for the case of Newtonian fluid s. (C) 1999 Academic Press.