Understanding the fluid mechanics behind transverse wall shear stress

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Title: Understanding the fluid mechanics behind transverse wall shear stress
Authors: Mohamied, Y
Sherwin, SJ
Weinberg, PD
Item Type: Journal Article
Abstract: The patchy distribution of atherosclerosis within arteries is widely attributed to local variation in haemodynamic wall shear stress (WSS). A recently-introduced metric, the transverse wall shear stress (transWSS), which is the average over the cardiac cycle of WSS components perpendicular to the temporal mean WSS vector, correlates particularly well with the pattern of lesions around aortic branch ostia. Here we use numerical methods to investigate the nature of the arterial flows captured by transWSS and the sensitivity of transWSS to inflow waveform and aortic geometry. TransWSS developed chiefly in the acceleration, peak systolic and deceleration phases of the cardiac cycle; the reverse flow phase was too short, and WSS in diastole was too low, for these periods to have a significant influence. Most of the spatial variation in transWSS arose from variation in the angle by which instantaneous WSS vectors deviated from the mean WSS vector rather than from variation in the magnitude of the vectors. The pattern of transWSS was insensitive to inflow waveform; only unphysiologically high Womersley numbers produced substantial changes. However, transWSS was sensitive to changes in geometry. The curvature of the arch and proximal descending aorta were responsible for the principal features, the non-planar nature of the aorta produced asymmetries in the location and position of streaks of high transWSS, and taper determined the persistence of the streaks down the aorta. These results reflect the importance of the fluctuating strength of Dean vortices in generating transWSS.
Issue Date: 11-Nov-2016
Date of Acceptance: 5-Nov-2016
URI: http://hdl.handle.net/10044/1/42979
DOI: http://dx.doi.org/10.1016/j.jbiomech.2016.11.035
ISSN: 1873-2380
Publisher: Elsevier
Start Page: 102
End Page: 109
Journal / Book Title: Journal of Biomechanics
Volume: 50
Copyright Statement: © 2016 The Authors. Published by Elsevier under a creative commons license (https://creativecommons.org/licenses/by-nc-nd/4.0/).
Sponsor/Funder: British Heart Foundation
British Heart Foundation
Funder's Grant Number: RE/08/002/23906
RM/13/1/30157
Keywords: Atherosclerosis
Hemodynamics
Planarity
Pulsatility
TransWSS
Wall shear stress
Biomedical Engineering
0903 Biomedical Engineering
1106 Human Movement And Sports Science
0913 Mechanical Engineering
Publication Status: Published
Conference Place: United States
Appears in Collections:Faculty of Engineering
Bioengineering
Aeronautics



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