Dielectrophoretic motions of a single particle in the vicinity of a planar wall under a direct-current electric field

• Numerically studied particle-wall dielectrophoretic (DEP) interactions.
• Applied a sharp interface method and a direct-forcing based immersed-boundary method.
• Integrated the Maxwell stress tensor to compute the DEP force on the particle.
• Understood the mechanism for occurrence of the wall-induced DEP motions.
• Examined effects of the gap between and conductivity set of the particle and wall.

We have numerically investigated two-dimensional dielectrophoretic motions of one particle induced due to interactions with a nearby planar wall under uniform electric field. Results show that the motions depend strongly on the gap between the particle and wall and their conductivity combination while the motion direction is determined uniquely by the wall conductivity. The particle is repelled to move farther away from the wall less conductive than the fluid, and vice versa. The motions become strengthened as either conductivity of the particle or wall deviates further from that of the fluid. Finally, the mechanism for the wall-induced DEP motions is examined.