FLOW-FIELDS IN A SIMULATED AXISYMMETRICAL TERMINAL ANEURYSM WITH SYMMETRICAL AND ASYMMETRIC OUTFLOWS

Laser-Doppler velocimetric measurements and flow visualization were pe rformed in a glass axisymmetric aneurysm model with symmetric and asym metric outflows through the branches. The bifurcation angle was fixed at 140 degrees, and the Reynolds number based on the steady bulk avera ge velocity and diameter of the afferent conduit was 500. The flow cha racteristics such as flow separation in the afferent conduit and flow activity inside the aneurysm for the symmetric and asymmetric outflow cases were compared in detail, and the case that is susceptible to thr ombosis was identified. In addition, the onset of transition from lami nar to turbulent flow inside the aneurysm was evidenced by the presenc e of vortex breakdown and the steep increase in the fluctuation level. Finally, the effect of pulsation on the flow pattern in the aneurysm was examined.