Abstract
Background
A valveless pump generates a unidirectional net flow of fluid around a closed loop of soft viscoelastic tubing that is rhythmically compressed at one point. The tubing must have at least two sections with two different stiffnesses. When a short segment of the tube is squeezed asymmetrically at certain frequencies, net flow of fluid around the loop can occur without valves.
Methods
Partial differential equations for the pressures, volumes, and flows define a simple one-dimensional model of such a pump, based upon elementary physical principles. Numerical computations on a personal computer can predict measured net flows.
Results
Net flow varies with the frequency and waveform of compression used to excite the pump, as well as with the site of compression and the stiffness and viscosity of the tubing. Net flows on the order of 1 ml/sec are obtained in a water-filled loop including 46 cm of stiffer plastic (Tygon) laboratory tubing and 70 cm of softer latex rubber tubing.
Conclusions
The heretofore mysterious phenomenon of valveless pumping can be described in terms of classical Newtonian physics, in which viscous damping in the walls of the pump is included. Studying valveless pumps in the laboratory and modeling their behavior numerically provides a low-cost, engaging, and instructive exercise for research and teaching in biomedical engineering.
Date of this Version
8-31-2010
DOI
10.1186/1475-925X-9-42
Recommended Citation
Babbs, Charles F., "Behavior of a Viscoelastic Valveless Pump: a Simple Theory with Experimental Validation" (2010). Weldon School of Biomedical Engineering Faculty Publications. Paper 13.
http://dx.doi.org/10.1186/1475-925X-9-42
Comments
This is the publisher pdf of Charles F Babbs. Behavior of a Viscoelastic Valveless Pump: a Simple Theory with Experimental Validation. BioMedical Engineering OnLine 2010, 9:42 (31 August 2010) and is available at: 10.1186/1475-925X-9-42.