Particle-Induced Electroconvection in Nonpolar Liquids.

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.