Effect of flow split on separation and stagnation in a model vascular bifurcation

Area of Science:

• Fluid dynamics
• Biomedical engineering
• Cardiovascular research

Background:

• Vascular bifurcations are prone to atherosclerotic plaque formation.
• Hemodynamic factors are implicated in the development of atherosclerosis.

Purpose of the Study:

• To investigate flow disturbances in an asymmetric vascular bifurcation model.
• To correlate flow patterns with the potential for atherogenesis.

Main Methods:

• Utilized a plastic model of an asymmetric vascular bifurcation.
• Employed dye injection and laser Doppler anemometry (LDA) for flow visualization and velocity measurement.
• Varied the proportion of flow exiting the sidearm (Qs/Qi) at a physiologic Reynolds' number (500).

Main Results:

• Boundary layer separation initiated at Qs/Qi = 0.19, spreading with increased sidearm flow.
• Near-wall velocity became negative within the separation zone at Qs/Qi = 0.31.
• At Qs/Qi = 0.38, separation enveloped the bifurcation, directing mainstream flow onto the divider.

Conclusions:

• Flow separation in vascular bifurcations creates regions of low wall shear stress.
• This separation pattern resembles sites of atherosclerotic plaque formation at the carotid bifurcation.
• Flow separation may be a significant contributor to atherogenesis.