Advective flow of permeable sphere in an electrical field

Advective flow of a permeable sphere in an electrical field is comprehensively studied. The sphere has a uniform permeability and is subject to an incoming Newtonian flow. The electrical field generates an electro-osmotic flow inside the sphere, which markedly affects sphere flow dynamics. A numerical model elucidates the effects of flow dynamic parameters on the drag coefficient and ratio of drag forces to a permeable and solid sphere. The model solves the Navier-Stokes equations both inside and outside the porous sphere. The unique flow field and pressure patterns of the permeable sphere flow are characterized in detail, and utilized to interpret the distinguishing flow behaviors of spheres induced by electro-osmotic flow. Drag force decreases and or reverses in direction when the intensity of the electro-osmotic flow in the sphere increases. When the electro-osmotic flow is counter to the incoming flow, drag force increases significantly, and vortices form near the sphere. As the sphere becomes highly permeable, the influence of the electro-osmotic flow and incoming flow velocity are reduced markedly. © 2009 Elsevier Inc. All rights reserved.