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Title:: Reconstruction of unsteady blood flow in intracranial aneurysms based on CT

Author(s):: XU Wentao; MUHTAR?Klimu; GAO Xiaxia; School of Mechanical Engineering,Xinjiang University,Urumchi 830047 China

Keywords:: Intracranial aneurysm; Computational fluid dynamics; Non-newtonian blood model; Numerical simulation; Heartbeat pulsation cycle; Wall shear force

摘要:: 选择Navier-Stokes方程作为颅内动脉瘤三维重建模型的不可压缩血液流动的数学模型，使用计算流体力学(Computational fluid dynamics,CFD)的方法对颅内动脉瘤模型进行非牛顿(non-Newtonian fluid)模型的非定常流的数值模拟。计算3个心跳脉动周期的数值，认为第三个心跳脉动周期为稳定周期并选择第三个周期为研究对象。分析了稳定周期内不同时刻血液动力学特性参数分布情况对颅内动脉瘤的形成、生长和破裂的影响。并将此结果与牛顿(Newtonian fluid)血液模型的流线、壁面剪切力、壁面压力分布特性进行对比。结果显示，非牛顿流体血液模型比牛顿血液模型更有可信度，比较符合真实血液的流动特性，在血液流动的心跳脉动周期内，非牛顿流体的（速度、压力、壁面剪切力等）分布更加平滑。过高的壁面剪切力会直接造成动脉瘤区域处破裂，过低的壁面剪切力会使血液的营养成为和代谢物遗留在血管区域导致血液粥样化的形成。

Abstract:: The Navier-Stokes equation was selected as a mathematical model for the incompressible bloodflow in a three-dimensional reconstruction model of intracranial aneurysms. The computational fluid method was used to simulate the non-Newtonian fluid (non-Newtonian)model of the intracranial aneurysm model. The values of three heartbeat pulsation periods were calculated, the third heartbeat pulsation period was considered as the stabilization period and the third period was selected as the study object. The influence of the distribution of hemodynamic parameters at different times during the stabilization period on the formation, growth and rupture of intracranial aneurysms were analyzed. This result was compared with the flow line, wall shear force, and wall pressure distribution characteristics of Newtonian fluid. The results show that the non-Newtonian fluid blood model is more credible than the Newtonian fluid blood model and more consistent with the true blood flow characteristics, during the heartbeat pulsation cycle of the blood flow, non-Newtonian fluids ( Velocity, pressure, wall shear, etc.)distribution is smoother. Excessive wall shear force will directly cause rupture in the aneurysm area. Too low wall shear force will make the nutrient of the blood and metabolites remain in the blood vessel area and cause the formation of blood aroma.