Understanding many micro-vascular diseases is aided by examining the dynamical behavior of blood cells. For instance, micro-vascular stenosis significantly influences the dynamics of red blood cells and hence causes several micro-vascular disorders. Thus, the objective of the current study is to numerically simulate cellular blood flow in stenosed micro-vessels with different stenosis severities and hematocrits to examine hemodynamic features which have important clinical implications. Red blood cells’ migration, velocity, and deformation are predicted. Furthermore, platelets’ margination and cell-free layer formation are examined. Accordingly, a three-dimensional numerical simulation of blood cells and their interaction with the surrounding plasma is considered. The simulation is performed using a validated code developed for cellular blood flows. Red blood cells’ migration and platelets’ margination are confirmed, which enhances the validity of the code. The obtained results report a high dependence of red blood cells’ migration and platelets’ margination on the hematocrit level, which agrees with other published studies. An asymmetrical cell-free layer thickness is exhibited along the stenosed vessel, with a maximum value at the throat of the stenosis, which greatly affects blood apparent viscosity and induces plasma skimming in this region. In addition, it is found that the cell-free layer thickness is strongly linked to stenosis severity and the hematocrit level. Due to its role in the endothelial cells’ function and structure, the wall shear stress is estimated. A reduction more than 75 % in the wall shear stress is obtained due to stenosis, with maximum values at the throat compared with the healthy case. The Fahraeus effect is examined, and the obtained results are compared with published experimental and computational works with an acceptable degree of agreement.

中文翻译：

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微血管狭窄严重程度和血细胞比容水平对红细胞动力学和血小板边缘化的影响：一项数值研究


通过检查血细胞的动力学行为有助于了解许多微血管疾病。例如，微血管狭窄显着影响红细胞的动力学，因此会导致多种微血管疾病。因此，本研究的目的是数值模拟具有不同狭窄严重程度和血细胞比容的狭窄微血管中的细胞血流，以检查具有重要临床意义的血流动力学特征。预测红细胞的迁移、速度和变形。此外，还检查了血小板的边缘化和无细胞层的形成。因此，考虑了血细胞及其与周围血浆相互作用的三维数值模拟。模拟是使用为细胞血流开发的经过验证的代码进行的。证实了红细胞的迁移和血小板的边缘化，这增强了代码的有效性。获得的结果报告了红细胞迁移和血小板边缘对血细胞比容水平的高度依赖性，这与其他已发表的研究一致。沿狭窄血管表现出不对称的无细胞层厚度，在狭窄的喉部达到最大值，这极大地影响了血液的表观粘度并在该区域诱导血浆撇去。此外，研究发现无细胞层厚度与狭窄严重程度和血细胞比容水平密切相关。由于其在内皮细胞功能和结构中的作用，估计了壁剪切应力。由于狭窄，壁剪切应力减少了 75% 以上，与健康病例相比，喉咙处的剪应力达到最大值。 检查了 Fahraeus 效应，并将获得的结果与已发表的实验和计算工作进行了比较，具有可接受的一致性。