Direct simulation on nonlinear thermokinetic phenomena due to induced-charge electroosmosis

Abstract

Previously, we proposed a novel mechanism to produce a nonlinear thermokinetic phenomenon (NTKP) around a metal cylinder in an electrolyte on the basis of analytical discussion. In this study, by using a non-steady direct multi-physics simulation technique based on the Stokes equation coupled with the electroosmotic equation that considers normal diffusion, electrophoresis and thermal diffusion, we directly verify the NTKP and show that the original driving force is the excess ions pressed on the particle by the thermokinetic force and that the NTKP vortex flow around the particle is generated by the interaction between the excess ion and the electric field that is made by the excess ions and/or the Seebeck electric field due to the blocking boundary condition on the wall. Namely, two types of NTKP exist and they are explained in a self-consistent manner by our new theory. In addition, through the discussion of a dielectric particle, we show that the NTKP is a general phenomenon that can be found in both metal and dielectric particles. We believe that our findings provide a new unified viewpoint to understand complex thermokinetic phenomena near metal and dielectric particles.