著者

Van Dyke M. 山根 隆一郎

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会誌 (ISSN:00214728)

巻号頁・発行日

vol.97, no.911, pp.825-827, 1994

著者

石川 拓司 大島 修造 山根 隆一郎

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.63, no.607, pp.789-797, 1997-03-25

被引用文献数

13

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It is well known that the fluid dynamics of arterial blood flow play an important role in arterial disease. The periodic blood flow through a stenosed tube with a moving wall is analyzed numerically. The Windkessel model is used to express arterial wall movement. A revised Casson model which is appropriate for numerical simulation is proposed as a constitutive equation of blood. The flow is assumed to be periodic, incompressible and axisymmetric. The influence of wall movement on flow through a stenosed tube is investigated. The flow pattern, separated region and the distributions of pressure and shear stress at the wall are obtained. The results show that the wall movement reduces the strength of vortex downstream of the stenosis and has considerable influence on the physical quantity of flow at the wall in one period. Therefore, it is concluded that the influence of wall movement should be taken into consideration for blood flow through a stenosed tube.

著者

多田 茂 大島 修造 山根 隆一郎

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.57, no.536, pp.1257-1264, 1991-04-25

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A numerical method employing physical components of the tensorial quantity as dependent variables on boundary-fitted curvilinear grids is applied to the simulation of flow in arbitrary cross-section curved pipes for an imposed pressure gradient of oscillatory nature. The basic equations are formulated for Stokes fluid. The computation for a Newtonian incompressible fluid in curved concentric annuli and curved eccentric annuli was carried out for the range 10^3 ≤ De ≤ 10^5, 1 ≤ Wo ≤ 10^2, where De is the Dean number and Wo is the Womersley number. It is found that, at very low or very high Womersley number, the amplitude of the wall shear stresses derived numerically is in good agreement with that of the zero-th order of the asymptotic expansions of the solution of concentric annuli as the curvature parameter δ tends to zero, and that 2 pairs of secondary flow appear for even low Womersley number, contrary to the case of the circular coiled tubes.

著者

奥井 健一 三上 房男 山根 隆一郎

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.57, no.538, pp.1973-1978, 1991-06-25

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The flow around two semi-infinite circular cylinders of the same diameter in the tandem arrangement at various spacings on a flat plate has been investigated experimentally. The cylinders were aligned with the axis normal to both the flat plate and the free stream. The time-mean surface pressures on the cylinders and the frequency of the vortex shedding in the direction of the cylinder axis were measured. The flow patterns on the cylinder were visualized using an oil-film technique and the flow visualization around the cylinders was performed by the liquid-parafine-mist technique. The flow patterns near the end of the cylinder were essentially different from two-dimensional flow. The flow passing along the end surface of the upstream cylinder became oscillating flow at the frequency lower than that of Karman vortex.