Ha Hojin, Lee Sang Joon
Department of Mechanical Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, Republic of Korea.
Department of Mechanical Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, Republic of Korea; Center for Biofluid and Biomimic Research, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang 790-784, Republic of Korea.
Med Eng Phys. 2014 Sep;36(9):1106-14. doi: 10.1016/j.medengphy.2014.06.004. Epub 2014 Jun 27.
The existence of swirling flow phenomena is frequently observed in arterial vessels, but information on the fluid-dynamic roles of swirling flow is still lacking. In this study, the effects of pulsatile swirling inlet flows with various swirling intensities on the flow field in a stenosis model are experimentally investigated using a particle image velocimetry velocity field measurement technique. A pulsatile pump provides cyclic pulsating inlet flow and spiral inserts with two different helical pitches (10D and 10/3D) induce swirling flow in the stenosed channel. Results show that the pulsatile swirling flow has various beneficial effects by reducing the negative wall shear stress, the oscillatory shear index, and the flow reverse coefficient at the post-stenosis channel. Temporal variations of vorticity fields show that the short propagation length of the jet flow and the early breakout of turbulent flow are initiated as the swirling flow disturbs the symmetric development of the shear layer. In addition, the overall energy dissipation rate of the flow is suppressed by the swirling component of the flow. The results will be helpful for elucidating the hemodynamic characteristics of atherosclerosis and discovering better diagnostic procedures and clinical treatments.
在动脉血管中经常观察到旋流现象的存在，但关于旋流在流体动力学方面作用的信息仍然匮乏。在本研究中，使用粒子图像测速速度场测量技术，对具有不同旋流强度的脉动旋流入口流对狭窄模型内流场的影响进行了实验研究。一个脉动泵提供周期性脉动入口流，具有两种不同螺距（10D和10/3D）的螺旋插入件在狭窄通道中诱导旋流。结果表明，脉动旋流通过降低狭窄后通道处的负壁面剪应力、振荡剪应力指数和血流逆转系数，具有多种有益效果。涡度场的时间变化表明，随着旋流干扰剪切层的对称发展，射流的传播长度变短且湍流提前爆发。此外，流动的整体能量耗散率受到流动旋流分量的抑制。这些结果将有助于阐明动脉粥样硬化的血流动力学特征，并发现更好的诊断程序和临床治疗方法。
