Significance of electrically induced shear stress in drainage of thin aqueous films

Abstract

We develop a novel model of drainage of microscale thin aqueous film separating a gas bubble and a solid wall. In contrast to previous studies, the electrostatic effects are accounted for not only in the normal but also in the shear stress balance at the liquid-gas interface. We show that the action of the tangential component of the electric field leads to potentially strong spatially variable shear stress at the deforming charged interface. This previously overlooked effect turns out to be essential for correctly estimating the long-time drainage rates. Comparison of time-dependent fluid interface shapes predicted by our model with the experimental data is discussed.

A simple collision model for small bubbles

“…no electrostatic forces are considered. This is justified since in the present study the lamella between bubble and obstacle remains thicker than about m 10 µ (equation ( 14) below), which is beyond the range of electrostatic forces adressed in [30,32] for example. During col lision, the bubble remains stable, i.e.…”