Flow separation behind a rib in a channel with laminar flow
V.M. Molochnikov1, N.I. Mikheev2, A.A. Paereliy3, K.R. Khairnasov4
1 Research Center of Problems of Power Engineering, Kazan Scientific Center, Russian Academy of Sciences, Kazan, Russia, vmolochnikov@mail.ru
2 Research Center of Problems of Power Engineering, Kazan Scientific Center, Russian Academy of Sciences, Kazan, Russia
3 Research Center of Problems of Power Engineering, Kazan Scientific Center, Russian Academy of Sciences, Kazan, Russia
4 Research Center of Problems of Power Engineering, Kazan Scientific Center, Russian Academy of Sciences, Kazan, Russia
Keywords: combined measurements, flow visualization, flow separation, laminar-turbulent transition, space-time structure, integral scale, large-scale vortical structures
Pages: 611-621
Abstract
Visualization data and results of combined measurements of flow quantities in flow with separation past a rib at nominally laminar regime of channel flow are reported. In the separation region, the flow is found to be essentially three-dimensional and unsteady, exhibiting a distinct cellular structure and flow zones with transverse motion. It is shown that the rib-induced flow separation gives rise to low-frequency fluctuations of flow velocity and initiates the turbulence transition in the channel flow. The critical Reynolds number at which flow instability starts developing in the channel is estimated. It is shown that at Reynolds numbers higher than the critical Reynolds number the linear integral scale of flow velocity fluctuations in the channel is defined by the duct size.
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