238 横風中の格子状配列大量ロッド群の振動パターンにおける複雑さ

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In this paper we discuss the flow-induced vibrations of a periodic array of cantilevered elastic rods in a steady, wind tunnel flow, transverse to the rods (Fig. A1). New experiments on the dynamics of 90 and 300 elastic oscillators in a steady cross flow are described. Our goal is to observe complex patterns in a large spatial array of oscillators as excited by fluid-elastic instabilities and impact between the vibrating rods. Unlike the single row dynamics, which lead to limit cycle behavior, multi-row arrays seem to exhibit chaotic though not necessarily, low dimensional dynamics, at a critical flow value. For Reynolds numbers exceeding 300 (based on the rod diameter.), the array of elastic rods undergoes increase, chaotic patterns of vibration consisting of momentary equilibria, motion along a linear path and elliptical path motions (Fig. A2). We introduced a symbolic measure of this pattern based on these three types of motion and use a pattern entropy measure to characterize the complexity (fig. A3). With increasing flow velocity however, organized wave-like structures appear to develop (Figs. A4 and A5). The corresponding array patterns are analogous to cellular automatic dynamics. Experimental models of this type may serve to help understand complex dynamics in large array heat exchange system. It may also be a model to understand wind crop dynamics and damage.
一般社団法人日本機械学会の論文
2000-09-01