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基于两种新型taylor-couette血液剪切装置的血液损伤规律研究

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基于两种新型Taylor-Couette血液剪切装置的血液损伤规律研究

作者：陆斌苏州大学

学位级别：硕士

随着人工心脏等机械循环支持装置在临床上的应用,血液相容性问题导致一系列术后并发症,包括溶血、血栓和消化道出血等,已经成为人工心脏发展的最大障碍。研究者们针对血液机械损伤问题通过设计搭建体外血液剪切平台进行大量的研究,发现... 详细信息

随着人工心脏等机械循环支持装置在临床上的应用,血液相容性问题导致一系列术后并发症,包括溶血、血栓和消化道出血等,已经成为人工心脏发展的最大障碍。研究者们针对血液机械损伤问题通过设计搭建体外血液剪切平台进行大量的研究,发现在非生理性环境中血液的损伤程度取决于剪切速率和暴露时间两个参数的大小,但目前关于这两个参数导致的确切血液损伤规律尚不明确,关于导致患者术后消化道出血的血管性血友病因子(von Willebrand Factor,VWF)的研究也不够深入。此外,在这些研究中采用的血液剪切装置普遍存在着结构缺陷影响实验结果,不利于血液损伤规律的研究。针对以上问题,本课题基于机制分析与数值模拟相结合设计了两种可以减少实验误差的新型taylor-couette血液剪切装置,并分别搭建了可模拟短暴露时间高剪切速率和长暴露时间低剪切速率状态的体外血液剪切实验平台,进行了血液损伤规律的研究,研究成果如下:(1)设计了两种可以减少血液额外损伤的新型taylor-couette血液剪切装置,一种用于研究高剪切速率、短暴露时间血液损伤规律的机械式taylor-couette血液剪切装置,另一种用于研究低剪切速率、长暴露时间血液损伤规律的磁悬浮taylor-couette血液剪切装置。根据两种装置的不同特性搭建模拟人工心脏不同状态的体外血液损伤平台。结果表明两种血液剪切装置可以有效的用于血液损伤规律的研究。(2)利用机械式taylor-couette血液剪切装置内部容积较小、可产生较高剪切速率的特点,搭建血液瞬时剪切实验平台研究红细胞的损伤规律。对血液进行短暴露时间高剪切速率的剪切实验制备检测样品,通过对各样品溶血指数的分析计算并使用MATLAB软件进行回归拟合,最终得到溶血指数关于剪切速率和暴露时间的经验公式。实验结果表明溶血指数与剪切速率和暴露时间的关系符合幂律模型,并发现造成严重溶血的剪切速率阈值约为21000 1/s,暴露时间阈值在1.2 s。(3)针对人工心脏中部分血液会循环暴露在非生理性环境中的状况,利用磁悬浮taylor-couette血液剪切装置搭建血液循环剪切实验平台研究VWF的损伤规律。通过分析高分子量VWF多聚体与低分子量VWF多聚体含量的变化以及VWF抗原和活性含量的变化,总结出关于VWF的损伤规律。研究结果表明,VWF的损伤主要表现为高分子量VWF多聚体含量的减少与低分子量VWF多聚体含量的增加,以及VWF活性的降低,但是VWF总量并不会发生显著的变化。此外,实验中造成严重VWF损伤的剪切速率阈值介于10000至15000 1/s之间,暴露时间阈值介于10至20 min之间。本文设计的实验装置可为血液损伤评价标准的建立提供装置方面的参考,同时实验结果能够为人工心脏等血液接触类医疗设备的设计优化提供一定的指导。

关键词： taylor-couette 剪切速率暴露时间血液损伤人工心脏

横向磁场作用下taylor-couette湍流流动的大涡模拟

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物理学报 2021年第18期70卷 210-218页

作者：董帅纪祥勇李春曦华北电力大学能源动力与机械工程学院保定071003

采用大涡模拟方法对横向磁场作用下导电流体taylor-couette湍流流动进行数值模拟,以研究其运动规律.计算模型为无限长度,半径比为1/2.雷诺数分别选取为3000和5000,磁场加载方式为全局磁场,哈特曼数取值0-50.对磁场作用下泰勒涡的演化过... 详细信息

采用大涡模拟方法对横向磁场作用下导电流体taylor-couette湍流流动进行数值模拟,以研究其运动规律.计算模型为无限长度,半径比为1/2.雷诺数分别选取为3000和5000,磁场加载方式为全局磁场,哈特曼数取值0-50.对磁场作用下泰勒涡的演化过程、速度分布和湍动能分布进行分析,并与轴向磁场作用下泰勒涡演化过程进行对比.结果表明:磁场对流场有显著的抑制作用,扭曲的泰勒涡在横向磁场的作用下破裂成小尺度涡结构,并沿磁场方向排列;在外圆筒和垂直于磁场方向的区域,磁场抑制效果较强;随着雷诺数的增加,磁场抑制效果减弱,在流场不同区域,流动呈现出不同的特点.与轴向磁场相比,横向磁场对流场的抑制效果较弱,流场分布呈现出明显的各向异性.

关键词：横向磁场 taylor-couette 流动湍流大涡模拟

Study on Performance of Laminar taylor-couette Flow with Different Developed Procedures

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Modern Mechanical Engineering 2012年第1期2卷 14-23页

作者： Xiantao Zhou Yan Shi Yinghuang Kong East China University of Science and Technology Shanghai China

The performance of laminar taylor-couette flow with different developed procedures is studied by the way of computational fluid dynamics (CFD) in steady state. In order to gain a group of developed procedure in CFD, a set of convergent solutions are used as the initial value of next boundary condition, and the new set of convergent solutions are regarded as developing from the previous steady state. Three groups of developed procedures are gained from the rotating speed series of inner cylinder, respectively from the gradual increase procedure (GIP), the gradual decrease procedure (GDP) and the sudden increase procedure (SIP). It is proved that the convergent solutions of fluid control equations are different when they are solved from laminar state with the same boundary condition, the same fluid property, the same mesh grid in CFD and the same business software except that the flow states have developed from the procedures of GDP, GIP and SIP. It is shown that the developed procedure could leave behind some information in the performance of the flow. In other words, the flow between concentric rotating cylinders has somewhat memory for the procedure of its history.

关键词： Laminar taylor-couette Flow Computational Fluid Dynamics Steady State Memory

Numerical study of bifurcation solutions of spherical taylor-couette flow

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Science China Mathematics 1996年第2期39卷 187-196页

作者：袁礼傅德薰马延文 LNM Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

The steady bifurcation flows in a spherical gap (gap ratio =0.18) with rotating inner and stationary outer spheres are simulated numerically for Reci 详细信息

The steady bifurcation flows in a spherical gap (gap ratio =0.18) with rotating inner and stationary outer spheres are simulated numerically for Reci

关键词： numerical simulation spherical taylor-couette flow non-unique solutions of N-S equations symmetry-breaking bifurcation.

Time Constants of the Transition between Onset and Decay Reynolds Numbers for the Appearance of taylor-couette Flow

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World Journal of Mechanics 2012年第2期2卷 77-83页

作者： Takashi Watanabe Graduate School of Information Science Nagoya University Nagoya Japan

We investigate the onset and the decay of taylor-couette flow in finite cylinders, and we report the estimated time scales in the azimuthal section of the flow state transition between the super-critical state and the sub-critical state by fitting the numerical result to the solution of the Stuart-Landau equation. The inner cylinder rotates, and the outer cylinder and both end walls of the cylinders are stationary. Near the end walls of the cylinders, the value of the time scale is small. In the inner region, the radial velocity component has a large time scale near the center of the vortices, while the axial velocity component has a large time scale between the vortices.

关键词： taylor-couette Flow Onset/Decay Flow Time Scale Stuart-Landau Equation

Behavior of Motile Sperm in taylor-couette Flow: Effect of Shear Stress on the Behavior of Motile Sperm

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Open Journal of Fluid Dynamics 2013年第2期3卷 9-13页

作者： Yasutaka Hayamizu Toru Hyakutake Koji Matsuura Shinichiro Yanase Shinichi Morita Shigeru Ohtsuka Takeshi Gonda Department of Mechanical Engineering Yonago National College of Technology Tottori Japan Graduate School of Engineering Yokohama National University Yokohama Japan Graduate School of Natural Science and Technology Okayama University Okayama Japan Research Core for Interdisciplinary Sciences Okayama University Okayama Japan

Infertility is often cited as one of the causes of a declining birthrate, which has become a serious social problem in recent years. Processes by which motile sperm can be safely and easily sorted are therefore important for infertility treatment. Therefore, as a new sorting method, microfluidic sperm sorter using the microfluidic system has been developed. To improve more separation efficiency of this device, it is necessary to know the behaviors of motile sperm in the microchannel where the sperm undergo shear flow. The previous study implied the necessity of the modeling of motile sperm in the shear flow. In the present study, therefore, we experimentally investigated the behavior of the motile sperm in the taylor-couette flow using PTV (Particle Tracking Velocimetry) method. The experimental results showed that the ascent of the shear stress led to the increase in the sperm velocity, and the direction of the sperm velocity was opposite to that of the flow.

关键词： Motile Sperm taylor-couette Flow Shear Stress PTV

Development and Flow Modes of Vertical taylor-couette System with Free Surface

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World Journal of Mechanics 2014年第3期4卷 90-96页

作者： Takashi Watanabe Yorinobu Toya Shota Hara Department of Mechanical Engineering Nagano National College of Technology Nagano Japan Graduate School of Information Science Nagoya University Nagoya Japan

We have numerically and experimentally investigated the flow modes of taylor-couette system consisting of coaxial two cylinders with vertical axes. The inner cylinder rotates and the outer cylinder and the bottom end of the cylinders remain stationary. The upper top boundary is the free surface of the working liquid between the inner and outer cylinders and it contacts with the air. While this flow appears in fluid machinery and chemical reactors and includes industrial interests, it also contains problems of fluid mechanics, which is about the behavior of the free surface in the rotating field. In this paper, we concretely show the developments of the one cell mode flow and the three cell mode flow at a small aspect ratio. We also represent the bifurcation diagram of the flow at the moderate aspect ratio about 5.5. In the numerical simulation, the flow is rest in the initial state, and the inner cylinder is linearly or suddenly accelerated to attain a flow with a prescribed Reynolds number. When the acceleration of the inner cylinder is high, an imperfect bifurcation occurs and the flows of the secondary modes emerge. At high Reynolds numbers, the flow first has many vortices and then some of the vortices collapse and the final stable flow arises. The loci of the normal five cell mode, the anomalous six cell mode and the secondary seven cell mode are determined.

关键词： taylor-couette System Vertical Cylinders Free Surface Flow Mode Mode Transition Bifurcation

taylor-couette湍流的直接数值模拟研究

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Taylor-Couette湍流的直接数值模拟研究

作者：杜珩中国科学技术大学

学位级别：硕士

本文采用直接数值模拟方法（DNS）研究了同心旋转圆筒taylor-couette湍流。详细讨论了雷诺数、半径比、外壁面反向旋转对大尺度taylor涡结构及湍流特性的影响。量化了taylor涡对湍流特征统计量的贡献,对相关的流动机制作了进一步的探讨... 详细信息

本文采用直接数值模拟方法（DNS）研究了同心旋转圆筒taylor-couette湍流。详细讨论了雷诺数、半径比、外壁面反向旋转对大尺度taylor涡结构及湍流特性的影响。量化了taylor涡对湍流特征统计量的贡献,对相关的流动机制作了进一步的探讨。通过研究雷诺数对taylor-couette湍流的影响发现,随着雷诺数的增大,流动湍化程度增强,具体表现为：内壁面剪切作用增强,湍流脉动峰值逐渐靠近内壁面;同时流场中的大尺度taylor涡结构渐渐扭曲,taylor涡对湍流统计量的贡献逐渐降低;高雷诺数下湍流脉动的生成、耗散和再分配等动力学过程增强,尤其是径向脉动对湍动能的再分配作用变得更为突出。通过研究半径比对taylor-couette湍流的影响发现,随着半径比的增大,随机脉动对湍流统计量的贡献减弱,而大尺度taylor涡的贡献增强。对于小半径比的taylor-couette湍流,流场主要是随机脉动占主导,并且有相当一部分湍动能是来自于流体径向脉动;而在大半径比情况下则是由大尺度taylor涡结构占主导,表现出了类似平板couette流动的特性。通过研究外壁面反向旋转对taylor-couette湍流的影响发现,在外壁面旋转速度较小时,taylor涡结构对湍动能和雷诺应力的生成、耗散和再分配等动力学过程具有重要影响;随着外壁面旋转速度的不断增大,湍流脉动的动力学过程主要由近壁区平均流的剪切作用主导,在中心区域流体运动主要由湍流随机脉动主导。

关键词： taylor-couette 湍流直接数值模拟 taylor涡