ANALYSIS OF VISCOUS MICROPUMPS AND MICROTURBINES

A numerical study of the three-dimensional viscous fluid flow in a nov el pump/turbine device appropriate for microscale applications is perf ormed. The device essentially consists of a rotating or free-to-rotate cylinder eccentrically placed in a channel, and is shown to be capabl e of generating a net flow against an externally imposed pressure grad ient, or, conversely, generating a net torque in the presence of an ex ternally imposed bulk flow. Full Navier-Stokes, finite-element simulat ions are carried out to study the influence of the width and other geo metric as well as dynamic parameters, and the results are compared to previous two-dimensional numerical and physical experiments. The three -dimensional simulations indicate a gradual decrease of the bulk veloc ity and pump performance as the two side walls become closer providing increased viscous resistance to the flow. However, effective pumping is still observed with extremely narrow channels. The utility of the d evice as a microturbine is also demonstrated for the first time in the present simulations. Particularly, the angular velocity of the rotor and the viscous torque are determined when a bulk velocity is imposed.