Equation of change for ellipsoidal drops in viscous flow

A simple phenomenological model for the deformation of a droplet immersed in a fluid subjected to a flow field with a uniform, but otherwise arbitrary, velocity gradient is presented. The model is capable of describing the transient evolution of the drop. The steady state predictions for simple shear and elongational flows are analytical. The model degenerates into Taylor theory in the limit of slow flows as well as for high viscosity ratios. It also recovers the affine deformation under the appropriate limiting conditions. The predictions are compared with some representative experimental and numerical results available in the literature. (C) 1998 Elsevier Science S.A. All rights reserved.