Analysis of compliant tube properties and operating conditions in a Liebau pump

Abstract

This study examines asymmetric pumping in Liebau pumps, a type of valveless pump that generates unidirectional flow through the periodic compression of a flexible (compliant) tube. This pumping has applications in biomedical devices, microfluidics, and organ support. We investigate how the properties of the compliant tube and the operating conditions affect the pump performance, using dimensionless parameters. Experiments were performed with different configurations, varying the tube material (latex and rubber) and the fluid (water and water–glycerine mixture). The results indicate that the flow rate and resonant period depend on the stiffness of the tube and the viscous effects. It was observed that for small values of the Womersley number (${Wo}^2$), viscous effects significantly reduce the flow rate. In contrast, for large Womersley values, the semiempirical models previously proposed adequately predict the experimental behaviour. Effects such as the compliant tube depression, which were not accounted for in previous models, were also found to influence performance. This work extends the analysis of this type of pump to unexplored conditions, with the aim of expanding knowledge and enabling the use of Liebau pumps in real-world applications.