Particle-Induced Electroconvection in Nonpolar Liquids

Abstract

We report the emergence of electrohydrodynamic (EHD) flow around colloidal particles suspended in oil when subjected to a uniform DC electric field. The flow is attributed to the Onsager–Wien effect, which generates bulk charge due to nonuniformities in the electric fields caused by particle presence. The flow pattern around conducting particles is quadrupolar, reminiscent of induced-charge electro-osmosis but in the opposite direction, whereas insulating particles produce a more complex flow structure. The experimental results agree well with theoretical predictions [Wang, Z.; et al.J. Fluid Mech.2024, 1000, A15.], demonstrating quantitative agreement beyond scaling relations. Beyond single-particle dynamics, the EHD flow can induce self-assembly and drive directional particle motion when multiple particles are present, offering new opportunities for flow control, directed self-assembly, and particle transport.