左內頸動脈瘤之三維重建與穩態血流數值分析

本研究乃針對實體左內頸動脈(LICA)瘤以非結構化網格有限體積離散方法模擬計算於不同雷諾數下的穩態流場特性。數值方法旨在求解不可壓縮Navier-Stokes方程組，其中對流項與擴散項分別採用二階上風差分法與二階中央差分法予以離散，並搭配SIMPLEC演算法來解決壓力與速度耦合問題。實體左內頸動脈瘤乃經由MRI（核磁共振攝影）擷取一系列之二維影像後再以自撰軟體予以重建其三維幾何結構。本文探討之人體左內頸動脈瘤其最大雷諾數?850、最小雷諾數300及平均雷諾數600。計算結果乃透過探討血液動力參數諸如瘤內速度向量場、渦漩結構、流入瘤體之流量、瘤壁剪應力及壓力分佈等來呈現瘤內血流動力特性。計算結果顯示血流皆經由瘤底開口(Orifice)靠近彎曲母管曲率外壁處流入瘤內，此發現可提供醫師於動脈瘤治療時，選擇人工支架(Stent)安裝位置之重要參考。此外，本文之數據分析更進一步確認出瘤頂?發生破裂之最可能位置。

關鍵字

左內頸動脈瘤；三維重建；數值計算；血流動力參數

並列摘要

The study aims to simulate the steady flow characteristics in the human left internal carotid arterial (LICA) aneurysm under various Reynolds numbers by numerically solving incompressible Navier-Stokes equations. Solutions were generated by an unstructured gird system and a cell-center finite volume method that used second-order upwind and center flux-difference splitting for the convection and diffusion terms, respectively. SIMPLEC algorithm was adapted to treat the pressure-velocity coupling problem. The three-dimensional (3-D) complex geometry of the human left carotid arterial aneurysm was reconstructed from a series of 2-D magnetic resonance imaging (MRI) data. The maximal, minimal, and mean Reynolds examined were 850, 300, and 600, respectively. Results are illustrated in terms of the hemodynamic factors such as intra-aneurismal velocity vector-field, primary vortex structure, inflow rate into the aneurysm, wall shear stress, and pressure distributions. The results show that the inflow into the aneurysm is mainly through the aneurysmal orifice along the outer wall side of curved parent vessel. This finding is believed to provide an important site reference for implanting a stent for the treatment of LICA aneurysms. A further analysis indicates that the aneurysmal dome is the most risky site for rupture.

並列關鍵字

Left internal carotid arterial aneurysm ； 3-D reconstruction ； Numerical computation ； Hemodynamic factors

國際替代計量

左內頸動脈瘤之三維重建與穩態血流數值分析

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