Temporal and spatial flow structures in a simulated vessel with stenotic lesion using time-resolved PIV technique

The stenotic geometry produces spatial and temporal regions such as high and low wall shear stress and flow separation. This disturbed blood flow in stenotic vessel can result in the further progress of atherogenesis. Therefore, the association between blood flow and geometrical factor need to be figured out by understanding the hemodynamic phenomena. The pulsatile flow features through a stenotic tube were investigated based on angiograms using a time-resolved particle image velocimetry (PIV) technique. A model of the tube core with stenosis was fabricated using a 3D printer, and the final tube model was fabricated with PDMS (polydimethylsiloxane). To prevent optical distortion, a mixture with glycerin and de-ionized water was used as the flow medium and a substitute for blood plasma. For PIV measurements, the concentration of fluorescence particles was controlled about 0.01 wt%. The flow rates were controlled using a circulating pump and silicon tubes from 1.6 to 3.7 mL/min. The pulsatile flow generates the local region of the maximum velocity at the post-stenosis and the shedding vortices move downstream over the time. The experiment indicates that such movements of vortices are quite different from the stagnant recirculation zone under the steady flow condition. With accumulating two-dimensional spatial flow fields obtained by phase averaging, the three-dimensional flow structure with the maximum velocity region was found to be a doughnut-shaped vortex ring.