急回転・急発進直後の円柱に作用する空力特性について(流体工学, 流体機械)

概要

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An initial lift force exerted by a quiescent fluid on a circular cylinder suddenly starting and rotating from rest is much complicated phenomena, because it results from the nonlinearity between the rotating and the translating motions. In the present paper, the lift coefficient, C_L, at the extremely early stage of motion is analytically obtained by using the matched asymptotic expansion method. The previous paper^(1) showed that C_L for time T→0 exhibited the T^-1/2 singularity at the low Reynolds number (Re<< 1), however, the present paper shows that C_L becomes asymptotically constant at Re=О (1), which is different from the theoretical prediction (C_L〜T^1/2) given by Badr & Dennis^(2) at Re >>1. Furthermore, the present paper shows that the dominant term of the initial drag coefficient, C_D, is the T^-1/2 singularity at three cases; Re<< 1, Re=О(1), and Re >>1.
社団法人日本機械学会の論文
2002-09-25