Kaliviotis Efstathios, Yianneskis Michael
Experimental and Computational Laboratory for the Analysis of Turbulence, Division of Engineering, King's College London, London, UK.
Biorheology. 2009;46(6):487-508. doi: 10.3233/BIR-2009-0555.
Existing time-dependent blood viscosity models that involve aggregation dynamics are mainly based on structural variables and/or viscoelastic models in order to describe the bulk mechanical properties of the fluid, but the implications of important characteristics of blood microstructure, such as the time- and flow-dependent characteristics of the red blood cell network developed due to aggregation at low shear rates, have not been thoroughly investigated. In this paper a time-dependent blood viscosity model is developed based on an energy-rate model previously proposed (Skalak et al., Biophys. J. 35 (1977), 771-781), which describes the total work needed to overcome the various forces developed between aggregated cells, including the adhesive, elastic and dissipative forces. Novel formulations of the forces acting on the fluid are developed and implemented in a volume-averaged version of the energy-rate model. The calculation of the viscosity is based on the relationship between the rate of energy changes and shear stress per unit volume of the fluid. The results show that network characteristics may significantly influence the viscosity blood at low shear rates and exhibit good agreement with experimental observations.
现有的涉及聚集动力学的随时间变化的血液粘度模型主要基于结构变量和/或粘弹性模型，以描述流体的整体力学性质，但血液微观结构的重要特征，如在低剪切速率下由于聚集而形成的红细胞网络的时间和流动依赖性特征，其影响尚未得到充分研究。本文基于先前提出的能量率模型（Skalak等人，《生物物理杂志》35（1977），771 - 781）开发了一个随时间变化的血液粘度模型，该模型描述了克服聚集细胞之间产生的各种力所需的总功，包括粘附力、弹性力和耗散力。作用于流体的力的新公式被开发出来，并在能量率模型的体积平均版本中得以实现。粘度的计算基于能量变化率与流体单位体积剪切应力之间的关系。结果表明，网络特征可能在低剪切速率下显著影响血液粘度，并且与实验观察结果表现出良好的一致性。
