Purpose

Carotid artery is often associated with plaque deposition because of its shape and associated flow features. The shape of stenosed bifurcation is characterised by bifurcation angle (ß), planarity angle (α) and severity of stenosis (b). In the present work, three-dimensional numerical computations have been performed to analyse the effect of these geometrical parameters of carotid bifurcation on the characteristics of flow.

Design/methodology/approach

Governing equations of this study were solved using ANSYS Fluent 20.1 and the blood flow was considered as laminar, pulsatile and non-Newtonian. Instantaneous flow behaviour has been illustrated using vorticity, velocity and helicity contours, whereas the time-averaged wall shear stress ( τw¯) and oscillatory shear index (OSI) quantify the time-averaged behaviour.

Findings

The recirculation zone and secondary flow are ascertained to be stronger for higher bifurcation angle as compared to the lower bifurcation angle. Strength of the secondary flow is found to reduce with increase in α from 0° to 10°, whereas it grows as α varies from 10° to 20°. For higher bifurcation angles, τw¯ is lower than 2 Pa and OSI is greater than 0.2 on the outer walls. Similar observations were made for τw¯ and OSI distribution on bottom wall in non-planar cases, which predicted atherogenic locations.

Originality/value

The values for ß were taken as 30°, 45°, 60° and 75°, whereas for α, range of 0°–20° was chosen. The stenosis was considered on the outer wall of internal carotid artery and its severity was considered within the range of 0%–60%.

中文翻译：

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通过分叉狭窄的颈动脉的搏动血流的血流动力学特征

 目的

颈动脉由于其形状和相关的流动特征，通常与斑块沉积有关。狭窄分叉的形状以分叉角 （ß）、平面角 （α） 和狭窄的严重程度 （b） 为特征。在本工作中，已经进行了三维数值计算来分析颈动脉分叉的这些几何参数对流动特性的影响。

设计/方法/方法

本研究的控制方程使用 ANSYS Fluent 20.1 求解，血流被认为是层流、脉动和非牛顿流。瞬时流动行为已使用涡度、速度和螺旋度等值线来说明，而时间平均壁面剪切应力 （τw ̄） 和振荡剪切指数 （OSI） 量化了时间平均行为。

 发现

与较低的分叉角相比，确定较高的分叉角的再循环区和二次流更强。发现二次流的强度随着α从 0° 到 10° 的增加而降低，而随着 α从 10° 到 20° 的变化而增加。对于较高的分叉角， τw ̄ 低于 2 Pa，外壁上的 OSI 大于 0.2。在非平面情况下，对底壁上的 τw ̄ 和 OSI 分布进行了类似的观察，从而预测了动脉粥样硬化的位置。

 原创性/价值

ß 的值取为 30°、45°、60° 和 75°，而 α 的范围为 0°–20°。考虑颈内动脉外壁狭窄，其严重程度被认为在 0%-60% 范围内。