周期的急拡大管路流れの不安定性と遷移(安定性(1),一般講演)

概要

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Stability of flow through a two-dimensional symmetric channel with multiple expanded sections and its transition are investigated numerically. The flow is often observed to be more unstable to oscillatory disturbances in more downstream sections than in upstream ones. We explore the origin of the appearance of instability in downstream sections at lower Reynolds numbers, in which we give an impulsive force at a point in the inlet part of the channel, and observe a packet of disturbance induced due to the forcing. The stability of the flow is determined from the numerical results and is compared with the results from the global stability analysis, which led us to a conclusion that the global instability occurs when the progression velocity of the tail of the packet vanishes. We also found that the convectively unstable disturbance destabilized in the upstream region augments the growth of disturbance in the downstream sections and leads to a global instability at lower Reynolds numbers.
日本流体力学会の論文
2010-09-09