動脈血管壁增厚造成血流阻塞，以致下游器官、組織等出現壞死情形，醫學上統稱為動脈硬化。此一疾病目前最廣為採用之治療方式為：繞道管手術，不過其術後的再發生率一直居高不下，除了病人生活習慣及手術選用之繞道管材質外，藉由許多血液動力學相關研究，可知血流流場與管壁病變有相當之關聯性，因此對繞道管流場的觀察及了解，對於手術改進可以提供一些物理上之資訊。
本文中採用SIMPLE-R計算規則，針對血管在不同阻塞情形之下的繞道管流場做數值模擬，藉由觀察其流場參數：壁面剪應力、分流率及迴流區等，歸納病變與特定流場型態之間的關係，並據此對手術提供建議。

Recently arterial diseases have become one of the most life-threatening diseases, and many studies have shown there is a great relation among blood flow patterns and arterial diseases. For this reason, identifying what fluid dynamic factors which favor the development of diseases become an important research area. In this thesis we focus the flow patterns in widely used by-pass surgery. With further understanding of the flow patterns, this work may facilitate and improve this surgery.
The present work analyzes the flow patterns in a complete by-pass tube under different severity stenosis conditions. By using SIMPLE-R algorithm with finite volume method , the three-dimentional,steady flow field is simulated numerically. The velocity profiles, secondary motions, location of flow reversed region and wall shear stresses are presented and discussed in this thesis.

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