Comparisons of different viscous pumps based on physical flow behavior

New scaling relations are given for flow behavior in viscous pumps which are characterized by two types of flow: (i) Couette-type or shear-driven flow and (ii) Poiseuille-type or pressure-driven flow. The equations describing these two types of flows are used to derive non-dimensional parameters to evaluate the pressure rise, flow rate, and important design characteristics of different viscous pump configurations. These provide means to make comparisons of relative performance for pumps of different size and configuration, and with different rotating speeds and different fluid viscosities. The non-dimensional parameters are also useful for comparing effectiveness of different viscous pump configurations, and for evaluating the effects of design changes to different configurations to maximize flow rate or pressure rise. (C) 2005 Elsevier B.V. All rights reserved.