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RESEARCH PAPERS

The Effects of Curvature on Fluid Flow Fields in Pulmonary Artery Models: Flow Visualization Studies

[+] Author and Article Information
P. G. Lynch, A. Saylor, A. P. Yoganathan

Cardiovascular Fluid Dynamics Laboratory, School of Chemical Engineering, Georgia Institute of Technology, Atlanta, GA 30332

B. Ha, C. Lucas, J. I. Ferreiro

Division of Cardiothoracic Surgery, University of North Carolina School of Medicine, Chapel Hill, NC 27514

G. W. Henry

Division of Pediatric Cardiology, University of North Carolina School of Medicine, Chapel Hill, NC 27514

J Biomech Eng 115(1), 97-103 (Feb 01, 1993) (7 pages) doi:10.1115/1.2895476 History: Received October 21, 1991; Revised May 18, 1992; Online March 17, 2008

Abstract

In vitro pulsatile flow visualization studies were conducted to assess the effects of varying radii of curvature of the right ventricular outflow tract (RVOT) and main pulmonary artery (MPA) on the flow fields in the main, right, and left pulmonary arteries of a one month lamb pulmonary artery model. Three glass flow-through models were studied; one with no curvature, one with the correct anatomic curvature, and one with an overaccentuated curvature on the RVOT and MPA. All other geometric parameters were held constant. Pulsatile flow visualization studies were conducted at nine flow conditions; heart rates of 70, 100, and 140 bpm, and cardiac outputs of 1.5, 2.5 and 3.5 l/min with corresponding mean pulmonary pressures of 10, 20, and 30 mmHg. Changes were observed in the pulmonary flow fields as the curvature of the outflow tract, heart rate and mean pulmonary pressure were varied. An increase in vessel curvature led to an increase in the overall radial nature of the flow field as well as flow separation regions which formed faster, originated further downstream, and occupied more of the vessel area. At higher heart rates, the maximum size of the separation regions decreased, while flow separation regions appeared earlier in the cardiac cycle and grew more quickly. Heart rate also affected the initiation of flow reversal; flow reversal occurred later in the cardiac cycle at lower heart rates. Both heart rate and mean pulmonary pressure influenced the stability of the pulmonary flow field and the appearance of coherent structures. In addition, an increase in mean pulmonary pressure increased the magnitude of reverse flow. These flow visualization observations have directed more quantitative studies such as pulsed Doppler ultrasound and laser Doppler anemometry velocity measurements.

Copyright © 1993 by The American Society of Mechanical Engineers
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