Investigating the impact of non-Newtonian blood models within a heart pump
Investigating the impact of non-Newtonian blood models within a heart pump
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DOI：
10.1002/cnm.2780
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发表时间：
2017-01-01
影响因子：
2.1
通讯作者：
Revell, A.
中科院分区：
文献类型：
--
作者：
Al-Azawy, Mohammed G.;Turan, A.;Revell, A.
对通过正排量左心室辅助装置的瞬态湍流血流进行了详细的计算流体动力学（CFD）研究。两种常见的非牛顿血流模型进行了比较，牛顿模型，以研究其对预测水平的剪切速率和壁面剪切应力的影响。鉴于这两个参数与血栓和溶血风险评价直接相关，因此需要评估脉动湍流内非牛顿流体效应建模的灵敏度，以确定CFD中的不确定性水平。为了捕捉湍流的影响，椭圆混合雷诺应力模型在本研究中使用，考虑到上级性能的二阶矩封闭方案先前确定的本作者。CFD配置包括两个循环旋转阀和一个移动推板，以周期性地改变腔室容积。一个重叠网格算法用于网格运动的每个实例，并采用零间隙技术，以确保阀门完全关闭。左心室辅助装置以86 BPM（每分钟心跳）的泵送速率和泵送周期的40%的收缩期持续时间操作，与进行比较的现有实验数据一致。变粘度模型的敏感性进行了研究，在平均流场，湍流水平和全球剪切速率，和一个无量纲指数是用来直接评估非牛顿效应的影响。沿着讨论建模不确定性，报告结果的临床相关性，观察到湍流动能通常预测在非牛顿流中高于在牛顿流中观察到的湍流动能。版权所有（C）2016约翰威利父子有限公司
A detailed computational fluid dynamics (CFD) study of transient, turbulent blood flow through a positive displacement left ventricular assist device is performed. Two common models for non-Newtonian blood flow are compared to the Newtonian model to investigate their impact on predicted levels of shear rate and wall shear stress. Given that both parameters are directly relevant to the evaluation of risk from thrombus and haemolysis, there is a need to assess the sensitivity to modelling non-Newtonian flow effects within a pulsatile turbulent flow, in order to identify levels of uncertainly in CFD. To capture the effects of turbulence, the elliptic blending Reynolds stress model is used in the present study, on account of superior performance of second moment closure schemes previously identified by the present authors. The CFD configuration includes two cyclically rotating valves and a moving pusher plate to periodically vary the chamber volume. An overset mesh algorithm is used for each instance of mesh motion, and a zero gap technique was employed to ensure full valve closure. The left ventricular assist device was operated at a pumping rate of 86 BPM (beats per minute) and a systolic duration of 40% of the pumping cycle, in line with existing experimental data to which comparisons are made. The sensitivity of the variable viscosity models is investigated in terms of mean flow field, levels of turbulence and global shear rate, and a non-dimensional index is used to directly evaluate the impact of non-Newtonian effects. The clinical relevance of the results is reported along with a discussion of modelling uncertainties, observing that the turbulent kinetic energy is generally predicted to be higher in non-Newtonian flow than that observed in Newtonian flow. Copyright (C) 2016 John Wiley & Sons, Ltd.