AM06-03-010 チャンネル流におけるLDV計測と可視化実験による限界レイノルズ数に関する実験(乱流渦構造(2),一般講演)

概要

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The purpose of this study is to investigate a process of relaminarization in a two-dimensional channel flow and to determine the minimal Reynolds number at which the flow keeps turbulent status. First, fluid velocity distributions in the channel flow were measured by LDV to obtain accurate Reynolds number of the flow. Secondly, flow visualization was made for observation of flow status. There are large scale streaks and small scale streaks in the relaminarization process. When the Reynolds number is 2000, the flow is filled with small scale streaks which seem to be original structures of turbulence. The Reynolds number decreases under 1700, structures with large scale streaks appear as patches in the small scale streaks. The Reynolds number is reduced less than 1100, the small scales streaks disappear though the large scale streaks still exist as patches in the laminar flow. Finally, when the Reynolds number is 1000, the large scale streaks vanish and the flow includes no disturbance. Relaminarization occurs gradually so that the transitional range is wide. There exists one critical Reynolds number of 1700 as the flow starts to contain the large scale streaks. The minimal Reynolds number for the turbulent disturbances is 1100 while the minimal Reynolds number for any disturbance is about 1000.
日本流体力学会の論文
2006-09-05