Study of three-dimensional electro-osmotic flow with curved boundary via lattice Boltzmann method

Abstract

A three-dimensional (3D) lattice Boltzmann model and boundary method is developed to simulate electro-osmotic flow (EOF) with a charged spherical particle immersed in an electrolyte solution. The general governing equations for electro-osmotic transport are Navier–Stokes equations for fluid flow and the Poisson–Boltzmann equation for electric potential distribution around the particle. Two sets of D3Q19 lattice structure with curved boundary conditions are implemented. The simulation results are compared with analytical predictions and are found to be in excellent agreement. The potential distribution appears circularly symmetric and the flow velocity decreases with the cross-sectional area for flow passage increasing due to the mass conservation. The effects of the ionic concentration, the sphere radius, electric potential and external electric field on the velocity profiles are investigated. The flow velocity increases with both the electric potential and the external electric field. However, the variation in flow velocity with the ionic concentration and the sphere radius is complex due to the change in electrical double layer (EDL) thickness.