Shear rate gradient in arteriolar bifurcations: theoretical and experimental

• Published in: Proceedings of the First Joint BMES/EMBS Conference : serving humanity advancing technology, Oct. 13-16, 99, Atlanta, GA, USA Vol. 1; pp. 208 vol.1 - 208
• Main Authors: Frame, M.D.S., Noren, D.P., Palmer, H.J.
• Format: Conference Proceeding Journal Article
• Language: English
• Published: IEEE 1999
• Subjects: Bifurcation; Cells; Computational modeling; Feeds; Fluorescence; In vivo; Mathematical models; Navier Stokes equations; Numerical models; Predictive models; Red blood cells; Shape; Shear stress
• ISBN: 0780356748; 9780780356740; 9780780356757; 0780356756
• ISSN: 1094-687X; 0589-1019; 1558-4615
• DOI: 10.1109/IEMBS.1999.802257

Our purpose was to determine whether the shear rate gradient through arteriolar bifurcations in vivo could be predicted from a model of low Reynolds (Re) divergent flow. The computational model (CFD-ACE) numerically solved 3D Navier-Stokes equations for a range of bifurcation angles (30-150/spl deg/) at low Re (0.01). The branch to feed diameter ratio was 4/5; the segment intersection shape was not held constant. Velocity profiles were determined in the feed, and at the start and end of the intersection. Calculated shear rate (dv/dr) predicted a significant increasing gradient along the branch wall, but not along the corresponding lateral wall, especially for the 90/spl deg/ angles. In vivo data were obtained from cremaster preparations of the anesthetized hamster. Fluorescently labeled red blood cells were flow tracers; velocity profiles were obtained at corresponding positions through a sequential series of arteriolar bifurcations, sampling the same range of angle and vessel dimensions. Calculated dv/dr showed an increasing gradient along the branch wall when angle was 80-120/spl deg/, but not for smaller angles, which generally occur further downstream in the network. The data suggest that both bifurcation shape and location within a flow network, together determine the shear gradient in vivo.