Stroke, Vol 12, 660-665, Copyright © 1981 by American Heart Association
FW LoGerfo, HM Crawshaw, M Nowak, E Serrallach, WC Quist and CR Valeri
This is a study of the flow disturbance in a plastic model of an asymmetric
vascular bifurcation. A sidearm was attached to the mainlimb at an angle of
15 degrees to the inlet flow axis. Water at steady flow was used and flow
patterns were demonstrated by a dye injection technique. The proportion of
inlet flow (Qi) exiting from the sidearm (Qs) was varied and flow patterns
were recorded photographically. A laser Doppler anemometer (LDA) was used
to measure near-wall velocity. At a physiologic Reynolds' number of 500, no
flow disturbance occurred in the mainlimb when the sidearm was completely
occluded. When the fraction of flow exiting from the sidearm (Qs/Qi)
reached 0.19, a region of boundary layer separation developed along the
wall of the mainlimb opposite the flow divider. This region of nearly
static fluid spread circumferentially around the mainlimb as Qs/Qi
increased. Near- wall velocity within the separation decreased and became
negative when Qs/Qi = 0.31. When Qs/Qi reached 0.38, the separation
enveloped the wall of the entire bifurcation with a shell of slowly moving
fluid. At the same time, the rapidly moving mainstream impinged directly on
the flow divider. There is a similarity between the region of separation
seen in this model and the site of formation of atherosclerotic plaque at
the carotid bifurcation. Separation may contribute to atherogenesis by
creating a region of low wall shear at bifurcations.
ARTICLES
Effect of flow split on separation and stagnation in a model vascular bifurcation
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