Experimental Investigation Of Flow Fields In The Curved Common Carotid Artery In Vitro

To study the flow field of the curved common carotid artery (CCA) is one of the essential subject of biomechanics in the area of hemodynamics. In recent years, the view on the carotid artery bifurcation asymmetry inlet velocity profile has been concerned and supported by scientists at home and abroad. Caro. et al (1992) investigated CCA morphology and hemodynamics through magnetic resonance (MR) angiography. In particular, they found an asymmetrical velocity distribution during systolic deceleration. They also observed that the CCA under investigation was characterized by aδ= 1:20 curvature ratio, and that the flow asymmetry tended to disappear when the neck was stretched in such a way that this curvature was completely avoided. Tortoli. et al(2003) used Doppler ultrasound technology to investigate the curved CCA, found the existence of M-velocity profile ("saddle-like") in the non-physiological unsteady flow conditions. This paper is the first to investigate flow fields of the curved CCA at the physiological condition by using PIV technology in vitro.Experimental models are incurvated glass pipes with straight pipe entrance, and their curvature ratios are 1:60(natural state) and 1:20 (bending state) respectively. Experimental Reynolds numbers divide into 315 (physiological average value), 722 (physiological peak value), 1061(Tortoli's value)and 2000(Limited value). Test locations are 0 0 ,30 0 ,60 0 ,90 0 of the incurvated glass pipe and test directions are bending plane and vertical plane. PIV signal after 30 tests for the average is then converted to velocity vector diagram. Additionally, we experiment the flow flied visualization of curved pipes and the PIV measurement of symmetric plane of the new TF-AHCB model.The results demonstrate that the bending morphology of the curved CCA leads to the asymmetric distribution of velocity on the pipe section. When the curved CCA is in a natural state and in the physical condition under the average flow Reynolds number, the skewed parabolic plate can be used to approximate the velocity profile in the pipe. As the curvature ratio and the Reynolds number increase, the velocity profile tends to be more complex. Besides the peak value on the bending plate moves more partially to the convex wall, the vertical plane appears the M-velocity profile. The results provide the experimental basis for the inlet velocity profile condition of carotid artery bifurcated pipe, also offer the reference data to the further experimental simulation and numerical simulation.