流動可視化를 利用한 동맥류 內部 流動 特性에 關한 硏究
A Study on the Flow Characteristics in the Aneurysm using Flow Visualization
v, 67 p.
유동가시화 동맥류 내부 유동특성;
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Aneurysm are frequently observed in the abdominal aorta, renal artery and cerebral arteries. Aneurysm is a vascular disease which is characterized by the dilatation of some portion of arterial wall. The formation and rupture of aneurysm cause significant mortality and morbidity rate. There are various factors, such as aging, genetic defects of biochemical factors, structural deficits of arterial wall, viral infection, which may influence the formation of aneurysm, but the stress cause by blood flow inside the aneurysm is believed one of the important factors that may influence the formation and rupture of aneurysm. Since the wall shear stress and pressure are important stress acting on the arterial wall, the blood flow characteristics, wall shear stress, turbulent stress and pressure distribution can provide important information in order to predict the formation and rupture of the aneurysm. Four abdominal aorta aneurysm models are constructed, and blood flow characteristics are measured in a mock circulation loop. Model 1 and model 3 have the maximum dilatation of 1.5 D(aorta diameter), and model 2 and model 4 have the maximum dilatation of 2D. Model 1 and model 2 are made with glass, and Model 3and model 4 are made with silicon. Wall shear rates are measured by flow visualization method incorporating a photochromic dye. Wall shear rate distributions are measured along the aneurysm wall. The minimum wall shear rates are observed near the 1D(D, aorta diameter) distal to the maximally dilated location, and the peak of wall shear rates are observed near 2D distal to the maximally dilated location. The temporal and spatial variation of wall shear rates are higher near the distal portion of aneurysm. Velocity fields inside the aneurysm are separated by two distinct region - central main flow region and near wall recirculation zone. The length of recirculation zone increases as the Reynolds number is increased for laminar flow, Velocity fluctuations are higher in the distal portion of maximally dilated location. Since the wall shear stress and pressure have maximum value, and velocity fluctuation and stress variation is higher in the distal portion of aneurysm, the distal portion of aneurysm is more prone to aneurysmal rupture.