Flow transitions in the surface switching of rotating fluid

• Published in: Journal of fluid mechanics 2009-10, Vol.636, p.475-484
• Main Authors: TASAKA, Y., IIMA, M.
• Format: Article
• Language: English
• Subjects: Deformation; Exact sciences and technology; Fluid dynamics; Free surfaces; Fundamental areas of phenomenology (including applications); Instrumentation for fluid dynamics; Measurement techniques; Physics; Reynolds number; Rotational flow and vorticity; Transition to turbulence; Turbulence; Turbulent flows, convection, and heat transfer; Vortex dynamics
• ISSN: 0022-1120; 1469-7645
• DOI: 10.1017/S0022112009991005

We study ‘surface switching’ quantitatively in flows driven by the constant rotation of the endwall of an open cylindrical vessel reported by Suzuki, Iima & Hayase (Phys. Fluids, vol. 18, 2006, p. 101701): the deformed free surface switches between axisymmetric and non-axisymmetric shapes accompanied by irregular vertical oscillation. Detailed simultaneous measurements showed that the magnitude of the velocity fluctuations (turbulent intensity) temporally varies greatly and are strongly correlated with the surface height, suggesting that dynamic switching between laminar and turbulent states is accompanied by vessel-scale surface shape changes. The study also identified clear hysteresis in the turbulent intensity arising from changes in the Reynolds number; the bifurcation diagram consists of two overlapping branches representing a high-intensity (turbulent) state and a low-intensity (laminar) state. Based on the results, a switching mechanism is suggested.