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Estimation of the turbulent viscous shear stress in a centrifugal rotary blood pump by the large eddy particle image velocimetry method
Journal of Hydrodynamics ( IF 2.5 ) Pub Date : 2020-06-22 , DOI: 10.1007/s42241-020-0036-y
Jing-jing Ji , Hao-yuan Li , Qing-yu Wu , Yu Zhang , Xian-wu Luo

The non-physiologic turbulent flows in centrifugal rotary blood pumps (RBPs) may result in complications such as the hemolysis and the platelet activation. Recent researches suggest that the turbulent viscous dissipation in the smallest eddies is the main factor of the blood trauma caused by the turbulent flow. The turbulent viscous shear stress (TVSS) was taken as the realistic physical force acting on the cells. However, limited by the temporal and spatial resolutions of the instrumentation currently available, very limited studies are available for the TVSS in the RBPs. In this paper, the large eddy particle image velocimetry (PIV) method is used to estimate the turbulent dissipation rate in the sub-grid scale, to investigate the effect of the TVSS on the blood trauma. Detailed flow characteristics, such as the relative velocity vectors, the estimated TVSS levels and the Kolmogorov length scales, are analyzed in three impeller phases at three constant flow rates (3 L/min, 5 L/min and 7 L/min). Over the measures range in this study, the maximum TVSS in the investigated RBP is lower than the reported critical value of stress. This study demonstrates that the large eddy PIV method is effective to evaluate the flow-dependent force on the cells. On the other hand, it is found that the TVSS is highly dependent on the flow behavior. Under severe off-design conditions, the complex flow characteristics, such as the flow separation and the vortical structures, will increase the TVSS. Thus, in order to reduce the hemolysis in the RBPs, the flow disturbance, induced by the departure of the incidence angle, should be avoided during the design of the RBPs.

中文翻译:

大涡粒子图像测速法估算离心式旋转血泵中的湍流粘性剪切应力

离心式旋转血泵(RBP)中的非生理湍流可能导致并发症,例如溶血和血小板活化。最近的研究表明,在最小涡流中的湍流粘性耗散是由湍流引起的血液创伤的主要因素。湍流的粘性剪切应力(TVSS)被当作作用在细胞上的实际物理力。但是,受当前可用仪器的时间和空间分辨率的限制,RBP中TVSS的研究非常有限。本文采用大涡流图像测速法(PIV)估算亚网格尺度的湍流耗散率,以研究TVSS对血液创伤的影响。详细的流量特性,例如相对速度矢量,估计的TVSS水平和Kolmogorov长度刻度在三个叶轮阶段中以三个恒定流速(3 L / min,5 L / min和7 L / min)进行分析。在本研究的测量范围内,所研究的RBP中的最大TVSS低于所报告的应力临界值。这项研究表明,大涡PIV方法可以有效地评估细胞上的血流依赖力。另一方面,发现TVSS高度依赖于流动行为。在严重的非设计条件下,复杂的流动特性(例如流动分离和旋涡结构)将增加TVSS。因此,为了减少RBP中的溶血,在RBP的设计期间应避免由入射角的偏离引起的流动扰动。
更新日期:2020-06-22
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