振動流中の円柱周りの流れの三次元数値解析 : 第1報,三次元流れ構造のクーリガン・カーペンタ数による変化(流体工学,流体機械)

概要

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Flows around a circular cylinder in oscillatory flow were studied by a numerical simulation using a finite-volume method. The computations were carried out by assuming 3-dimensional (3-d), unsteady, incompressible and viscous flow through Keulegan-Carpenter number (KC) in the range 3≦KC≦25 at Stokes number (β) of 95. The predictions obtained by 3-d computations were compared with experimental results by using a U-tube water tank. As a result, typical flow-patterns induced by oscillatory flow, for example, "longitudinal vortices" at KC=3〜4, "transverse-vortex street" around KC=12, "double-pair pattern" around KC=16 and "wake vortex street" at KC≧20 were able to be successfully reproduced. The computed flow-patterns were in good agreement with experimental results. The collapse of 3-d vortical cell-structure at KC=5 causes a temporal change of the direction of vortex-shedding. Furthermore, it is found that the flow-patterns of transverse-vortex street, double-pair and wake vortex street have the 3-d vortical structures which changes complicatedly in the span-direction.
社団法人日本機械学会の論文
2002-02-25