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DEVELOPMENT OF A TURBULENT SPOT INTO A STRIPE PATTERN IN PLANE POISEUILLE FLOW

Hiroshi Aida
Department of Mechanical Engineering Tokyo University of Science Chiba, Japan

Takahiro Tsukahara
Tokyo University of Science

Yasuo Kawaguchi
Department of Mechanical Engineering, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-8510, Japan

Аннотация

A structure consisting of quasi-laminar and turbulent regions in a stripe pattern, which can be found in a transitional plane channel flow, is called 'turbulent stripe'. In the previous works, the emergence of this structure was confirmed only in the case of decreasing Reynolds number from turbulent regime. In the present study, its formation from a turbulent spot has been investigated using a direct numerical simulation in a relatively large-scale computational domain of Lx × Ly × Lz = 731.4δ × 2δ × 365.7δ at Reτ = 56 and Lx × Ly × Lz = 640δ × 2δ × 320δ at Reτ = 64. We observed the stripe pattern of quasi-laminar and turbulent regions inside of the spot. However, the turbulent eddies decayed more rapidly for Reτ = 56 than those for Reτ = 64. The developed spot at Reτ = 64 was found to be different form from that at Reτ = 56.