Adaptive two capacitor model to describe slide electrification in moving water drops

Abstract

Slide electrification is a spontaneous charge separation between a surface and a sliding drop. Here, we describe this effect in terms of a voltage generated at the three-phase contact line. This voltage moves charges between capacitors, one formed by the drop and one on the surface. By introducing an adaptation of the voltage upon water contact, we can model drop charge experiments on many surfaces, including more exotic ones with drop-rate dependent charge polarity. Thus, the adaptive two capacitor model enables new insights into the molecular details of the charge separation mechanism.