Modelling drop-drop interactions in an atomic force microscope

Abstract

Recent experimental developments enabled dynamical measurement of the force between two moving oil drops in solution using an Atomic Force Microscope. The drop sizes (about 40 microns) and velocities (up to 15 microns/s) of the experiments produce a regime where surface forces, hydrodynamics and drop deformation are all significant. A detailed model of the experiments developed by Carnie, Chan, Dagastine, Lewis and Manica (2004) produces calculated force curves with attractive forces due mainly to hydrodynamic lubrication forces, in agreement with experiment. Details of the evolution of the drop surface deformations and surface velocity profiles are included in movies accompanying this paper..