| Co-Investigator(Kenkyū-buntansha) |
UJIIE Hiroshi Tokyo Women's Medical University, Neurosurgery, Research Associate, 脳神経外科, 助手 (00138869)
KUDO Susumu Shibaura Institute of Technology, Mechanical Engineering, Lecturer, 工学部, 講師 (70306926)
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| Research Abstract |
The aneurysm in the cerebral artery is apt to initiate around the "Circle of Willis". The anterior communicating artery (ACoA), which composes one of major part of the circle of Willis, is the most predilection artery of the aneurysm. In the present study, the change of flow structure such as the wall shear stress at the apex of ACoA with the initiation of aneurysm is described in steady flow. Once the early aneurysm initiates at the apex in one con fluent tube with much flow rate, the distribution of wall shear stress abruptly changes around the early aneurysm. The relation between the initiation and the development of aneurysm is physiologically discussed from the viewpoint of hemodynamics. The flow field around ACoA is simulated by two con fluent tubes joining at the angle of 60 degrees, two parallel bifurcating tubes, and the junctional tube, bypass (ACoA), connecting four tubes at normal condition. The flow model with the early aneurysm is simulated as the concave with small radiu
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s around the apex in the right con fluent tube with much flow rate. In experiment, the velocity profile is measured by LDA and the wall shear stress is estimated from the velocity gradient near the tube wall. The saturated sodium iodide NaI solution with the same refractive index of 1.49 as the channel material, acrylic plate, is employed as the working fluid in velocity measurement. The measurement has been carried out at the Reynolds number of Re=2R_oU/v=400 and the con fluent ratio of Q_R/Q_L= 2.2. U is the mean velocity based on the average flow rate and v is the kinematic viscosity. Except for the flow field around the early aneurysm, the velocity profile around ACoA as a whole is similar to that without the aneurysm at normal condition. The velocity through ACoA is several times as large as the maximum velocity in the right con fluent tube. The core flow in the right con fluent tube impinges at the right apex, right medial corner. There is a small recirculating flow in the concave, aneurysm. Less
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