Flow under rotation is widely encountered in geophysics, astrophysics, and engineering, such as oceanic flows, atmospheric flows, and flows in turbomachinery. Wall turbulence remains a fundamental problem in fluid mechanics. In wall turbulence, system rotation has a significant impact on the multiscale dynamics and coherent structures of turbulence. Therefore, investigating the influence of system rotation on the multiscale dynamics of wall turbulence is of crucial importance for a deeper understanding of the nature of wall turbulence under rotation and for predicting, optimizing, or controlling relevant flows in nature and engineering.
Associate Research Fellow Changping Yu and Research Fellow Xinliang Li at the Institute of Mechanics, Chinese Academy of Sciences, recently conducted a study on the multiscale dynamics in streamwise-rotating channels. The research first utilized the generalized Kolmogorov equation to investigate the impact of rotation on the energy balance of wall turbulence, during which the multiscale characteristics of inclined vortices were first discovered. Subsequently, through the Reynolds stress equilibrium equation and the hairpin vortex model, it was inferred that Coriolis force and pressure-velocity correlation are the main factors maintaining inclined vortices, with the Coriolis force exhibiting dual effects. The study delved into the multiscale characteristics and maintenance mechanisms of rotating channel turbulence, providing valuable insights into the impact of rotation on turbulent states in general wall flows.
The work, titled "Multiscale dynamics in streamwise-rotating channel turbulence," was published in the Journal of Fluid Mechanics. Ruining Hu, a Ph.D. student at the Institute of Mechanics, Chinese Academy of Sciences, is the first author of the paper, with Associate Research Fellow Changping Yu as the corresponding author and collaboration with Research Fellow Xingliang Li. The research received support from the National Key Research and Development Program (2019YFA0405300, 2020YFA0711800) and the National Natural Science Foundation of China (12072349, 12232018, 91852203, 12202457).
Link：https://doi.org/10.1017/jfm.2023.691
Figure1. Vortex in rotating channel turbulence, colored by the wall-normal distance
Figure2. The mechanisms related to (a) ejections and (b) sweeps in the hairpin vortex models