The flow of liquids near charged interfaces and some of its applications
Sandip Ghosal, Associate Professor
Department of Mechanical Engineering
Northwestern University
ABSTRACT: Matter is electrically neutral on macroscopic scales, but interfaces of materials are almost always charged. We are reminded of this in small ways in our daily lives; for example a nylon comb or a plastic ruler will attract bits of paper and deflect a narrow stream from a faucet if you first rub it on your clothes or hair. These interfacial forces being proportional to the surface area are however often dwarfed by volume forces such as gravity. The situation changes dramatically on very small scales (roughly a 100 micron or less). At an interface of a solid and liquid, these electrical forces can drive a significant flow. Such micro-scale flows have important applications in recently developed and rapidly evolving technologies such as microfluidics and nanotechnology. In this talk I will first introduce the mathematical tools for describing such small scale electrically driven flows and then illustrate with some recent applications.