Effect of inertia on drop breakup under shear

A spherical drop, placed in a second liquid of the same density and viscosi ty, is subjected to shear between parallel walls. The subsequent flow is in vestigated numerically with a volume-of-fluid continuous-surface-force algo rithm. Inertially driven breakup is examined. The critical Reynolds numbers are examined for capillary numbers in the range where the drop does not br eak up in Stokes flow. It is found that the effect of inertia is to rotate the drop toward the vertical direction, with a mechanism analogous to aerod ynamic lift, and the drop then experiences higher shear, which pulls the dr op apart horizontally. The balance of inertial stress with capillary stress shows that the critical Reynolds number scales inversely proportional to t he capillary number, and this is confirmed with full numerical simulations. Drops exhibit self-similar damped oscillations towards equilibrium analogo us to a one-dimensional mass-spring system. The stationary drop configurati ons near critical conditions approach an inviscid limit, independent of the microphysical flow- and fluid-parameters. (C) 2001 American Institute of P hysics.