円筒容器内渦崩壊に自由表面と固体壁面の及ぼす影響についての数値的研究 : アスペクト比h=2.0の場合

概要

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Numerical study is conducted on the vortex breakdown flows in a cylindrical container with rotating bottom disk. The flows are driven by the bottom disk rotating at a constant angular velocity. The aspect ratio h of the cylindrical container is fixed at a value of h=2.0. The top disk of the continer is assumed to be a flat undeformable free surface and the flow axisymmetry is also assumed. The Ψ-Ω method is utilized and numerical solutions are obtained for the Reynolds number Re within the range 1000≤Re≤3000 which covers the steady and unsteady flows. Numerical solutions are also obtained for a cannonical problem of top rigid wall vortex breakdown flows. Results are compared with the existing experimental data for both problems. The comparison exhibited gross similarity to the experimental visualization by Spohn et al.for the free surface flows and Escudier, for the top rigid wall flows. However, close investigation disclosed that the critical Reynolds number Re_c for the onset of breakdown bubble and Re_c for the attachment of recirculating bubble to the free surface are different from those reported by Spohn et al. By comparing the present free surface flow solutions with those obtained for the cannonical problem, the effect of free-slip boundary condition on the occurence of vortex breakdown is quantitatively described.
一般社団法人日本機械学会の論文
2000-03-25