Effects of channel curvature on the performance of viscous micro-pumps

Abstract

The effects of channel curvature on the performance of viscous micro-pumps with a circular channel were numerically investigated using the Navier-Stokes equations. Channel curvature was defined as the reciprocal of the radius of a circular arc along the centerline of the channel. The performance of viscous micro-pumps was studied in terms of the dimensionless mass flow rate and dimensionless driving power. To study the effects of channel curvature, various pumps were simulated by varying the radius and height of the channel, and the eccentricity of the rotor. Numerical results show that the channel curvature plays a significant role in the performance of viscous micro-pumps. The effects of channel curvature become more significant as the channel height increases and/or the clearance gap decreases. For a given pump geometry and operation conditions, there is an optimal channel height that results in a maximum dimensionless mass flow rate. The value of optimal channel height is shown to be quite dependent on the magnitude of channel curvature and the pressure load. The dimensionless driving power decreases monotonically with channel curvature; thus a viscous micro-pump with a circular channel is more efficient than a corresponding pump with a straight channel. A circular channel viscous micro-pump exhibits a larger mass flow rate than a corresponding pump with a straight channel for all the Reynolds numbers simulated in this paper.