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Abstracts: ASAIO Bioengineering/tissue Engineering Abstracts

A PARTICLE IMAGE VELOCIMETRY INVESTIGATION OF PULSTILE FLOW IN A TOTAL ARTIFICIAL LUNG MODEL EXPERIMENT

Lin, Yu-chun1; Bull, Joseph L1

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This study experimentally examined the effects of pulsatility on the flow behind a cylinder as a model of flow in a total artificial lung (TAL). The TAL consists of hollow fibers through which the oxygen-rich air flows. Gas exchange occurs between the gas inside the fibers (cylinders) and blood that flows around the fibers. Since the gas diffusivity and diameters of cylinders are both small, the Peclet number is large and convection dominates. Secondary flows are expected to increase mixing and enhance gas transport. Blood flow in the TAL is driven entirely by the right ventricle, and, therefore, the flow is pulsatile. Steady flow after a cylinder has been investigated extensively, but little is known about the effects of pulsatility. Using the particle image velocimetry (PIV) method, we investigated pulsatile flow around a cylinder in a water tunnel and assessed the effects of frequency and amplitude of pulsatility, and average flow rate. It is shown that the vortices formed at a lower Reynolds number in pulsatile flow than steady flow. Preliminary studies indicate there is a critical value of the Stokes number from 0.2 to 0.37 and a critical value of the Reynolds numbers between 1 to 5. For Stokes and Reynolds numbers below these critical values, vortices did not form. Consequently, higher Stokes and Reynolds numbers are expected to enhance transport. However, increased gas exchange may occur at the expense of increased resistance, and an optimal TAL performance will require consideration of both effects.

Copyright © 2005 by the American Society for Artificial Internal Organs