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ISSN On-line: 2152-209X
VORTICAL STRUCTURE DYNAMICS OF SEPARATED CHANNEL FLOW BEHIND A SEMICYLINDRICAL RIB AT LATE STAGES OF LAMINAR-TURBULENT TRANSITION
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RESUMO
Results of visual research of the flow structure dynamics in the region of flow separation behind a semicylindrical rib in a channel at transitional flow regimes are presented. Smoke-wire flow visualization was recorded by a high-speed camera. Experiments were conducted in the range of Reynolds numbers 370−4200 calculated using the channel height. Successive stages of the shear layer stability loss behind the rib and generation of spanwise vortices were observed. Reynolds numbers corresponding to the shear layer instability onset were defined. Some features of dynamics of the vortex generation onset region were described. Most probable scenarios of vortex evolution in the flow reattachment region were revealed. Large-scale vortex generation frequencies depending on Reynolds number were estimated. Possible mechanism of vortex generation at the late stages of transition to turbulence in separated flows was described.
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