颅内直的/微弯母管动脉旁瘤的三维稳态流/脉动流的数值模拟

Three-Dimensional Steady/Pulsatile Flow Numerical Simulation of Blood Flow for Intracranial Lateral Aneurysm with a Straight/Slight Curved Parent Vessel

对颅内直的或微弯母管动脉旁瘤的血液动力学进行数值模拟。在血液为不可压缩、牛顿流体和刚性血管假定下,利用人工压缩性方法求解三维N-S方程。在稳态和脉动情况下,计算了流动压力、剪应力、入流体积及速度场和压力场。基于管径的最大/最小Reynolds数是475/152,Womersley数是2.5,这些值表示了中等脑动脉。计算结果表明,在瘤颈的近端和远端应力集中,直管旁瘤比微弯的母管旁瘤的应力更集中,而且在一个脉动周期的大部分时间里,微弯母管的入流速率高于直母管的入流速率;压力有两个极大值,分别出现在瘤的顶部和瘤颈的近端;在一个周期内,流动方向和流入瘤中的流量的快速变化,导致瘤的远端和近端剪应力的压力快速变化,从而连续地损伤瘤颈的内膜,其后可能导致瘤的生长或再生。

Blood flow of lateral aneurysm modes with a straight/slight curved parent vessel was numerically simulated. The computations were carried out under incompressible, viscous, Newtonian flow, non-elasticity of the wall conditions by using an artificial compressibility algorithm to solve three-dimensional N-S equations. Flow pressure, wall shear stress, inflow volume and velocity/pressure field were calculated in the steady and pulsatile conditions. The maximum/minimum Reynolds number was set at about 475/152 based on diameter of parent vessel. The Womersley number was set to 2.5. These values are a representative of the middle cerebral arteries in vivo data. The significant results show that lateral saccular aneurysms subjected to wall shear stress concentration at proximal and the distal ends of cavity neck and more concentration for a straight parent vessel than slight curved vessel. It is observed that higher inflow rate from parent into cavity for slight curved than straight parent vessel in the most of time during a flow cycle. Two maximum pressure appear at proximal and aneurysm dome respectively, and rapid changes of blood flow direction and inflow quantity during a flow cycle result in rapid changes in inflow volume, wall shear stress and pressure at the proximal and distal wall of the cavity. The rapid changes would make continuous damage to the intima at the cavity neck and could lead to subsequent aneurysm growth or regrowth.