利用非均匀格Boltzmann方法研究支架对颅内动脉瘤血流动力学的影响

目的 研究截面为不同旋转角度的三角形支架对颅内动脉瘤血流动力学的影响。方法采用非均匀格子Boltzmann方法对支架区域进行局部加细，并结合曲边界处理格式对置入支架的颅内动脉瘤进行数值模拟。通过对动脉瘤内流动形态、瘤口速度、瘤内速度减小量等动力学参量的分析，探讨不同旋转角度支架用于治疗颅内动脉瘤的效果。结果 在减小瘤内血流速度方面，旋转角为180°的三角形截面支架效果最好，无旋转的三角形截面支架引起的速度减少量最小。在孔隙率较低情况下，截面为不同旋转角度的三角形支架起到效果差异较小。结论 非均匀格子Boltzmann方法结合曲边界处理格式可以较准确地研究动脉瘤血流动力学特性，为支架的设计提供参考依据，并为临床介入治疗法提供一定的指导。
Objective To investigate the effects of triangle stents with different rotation angles on hemodynamics of cerebral aneurysms. Methods A non-uniform lattice Boltzmann method (LBM) was adopted to make local refinement on grids near the stent, and a scheme for the curved boundary conditions was used to numerically simulate the stented cerebral aneurysms. The stream plots of flows in the aneurysms, the velocity profiles at the aneurysm orifice and the velocity reduction were obtained and analyzed to evaluate the effects of stents with different rotation angles on treating cerebral aneurysms. Results With respect to velocity reduction, the best treatment effect was achieved in the triangle stent with rotation angle of 180°, while the triangle stent without any rotation caused the smallest velocity reduction. In addition，the dynamic differences were not obvious in triangle stents with different rotation angles at small porosities. Conclusions The non-uniform LBM combined with curved boundary conditions can be used to study hemodynamic characteristics of the cerebral aneurysm accurately, which provides reference for the design of such stent and also offers some guidance for intervention therapy in clinic.