Ion-driven air flow is a novel method of pumping air at microscale dimensions using the concept of ion drag. The method employs a series of micro-fabricated electrodes to generate strong electric fields that pump unipolar ions through air. Ions collide repeatedly with neutral molecules, thus generating bulk motion of the gas. Meso-scale motion is obtained by changing the voltage of electrodes rapidly over time to create a nearly continuous force on the ions. One application of this technology involves generation of air flow through microchannels or other micro-featured surfaces to create compact, high flux heat sinks for electronics cooling. A numerical model of the fluid-ion-electric field interaction has been developed. The momentum and continuity equations are supplemented with equations for electric charge transport and for electric potential. The momentum equations are coupled through a body-force term to the charge transport and electric field equations, both of which are coupled to the momentum equations and to each other through source and convection terms. The model describes the one-dimensional, time-dependent flow of air and ions between evenly spaced microscale planar electrodes, of which the voltages are switched at frequencies on the order of 1 MHz. The flow is investigated to determine the effect of switching frequency on maximum velocity and pressure head.

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