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THE INFLUENCE OF A MULTIPLE-HARMONIC PULSATILE WAVEFORM ON THE SECONDARY FLOW IN A CURVED TUBE

Chekema Prince
Department of Biomedical Engineering, Polytechnic Institute of New York University 6 Metrotech Center, Brooklyn, NY 11201

Sean D. Peterson
School of Mechanical Engineering Maurice J. Zucrow Laboratories, Purdue University West Lafayette, Indiana 47907 USA; Department of Mechanical and Mechatronics Engineering University of Waterloo 200 University Avenue West, Waterloo, Ontario, Canada

Michael W. Plesniak
Maurice J. Zucrow Laboratories (formerly Thermal Sciences and Propulsion Center), School of Mechanical Engineering, Purdue University, West Lafayette, Indiana, USA; Department of Mechanical and Aerospace Engineering The George Washington University

要約

Under the application of a harmonically oscillating pressure gradient of sufficiently high frequency, the dominant secondary flow pattern in a curved tube exhibits inward centrifuging. The present study investigates the spatial and temporal evolution of the secondary flow structure in a curved tube driven by a physiologically-inspired pulsatile waveform. Specifically, the study seeks to address whether an inward centrifuging secondary flow structure (Lyne-type vortices) is possible with a nominally low-frequency input waveform. Experimental data were acquired using Laser Doppler Velocimetry (LDV). Experimental results show that fully developed flow is established after negotiating approximately 150° of the 1/7 radius to radius of curvature bend arc. In the developing region, Lyne-type vortices are observed to develop spatially along the curved pipe. At the peak of the input waveform, these vortices develop near the outer wall of the bend 90° from the bend entrance and become more centralized downstream. At the fully developed region the Lyne-type vortices become prominent within the cross-section of the bend. Temporally, the Lyne-type vortices are observed to develop near the outer wall during the acceleration phases of the waveform, become centralized at the peak of the waveform, and move back toward the outer wall during the deceleration phases. Emergence of complex secondary flow structures at low oscillation frequencies may have applications in low speed mixing and in stent design.