Laminar–Turbulent Intermittency in Annular Couette–Poiseuille Flow: Whether a Puff Splits or Not

Abstract

Direct numerical simulations were carried out with an emphasis on the intermittency and localized turbulence structure occurring within the subcritical transitional regime of a concentric annular Couette–Poiseuille flow. In the annular system, the ratio of the inner to outer cylinder radius is an important geometrical parameter affecting the large-scale nature of the intermittency. We chose a low radius ratio of 0.1 and imposed a constant pressure gradient providing practically zero shear on the inner cylinder such that the base flow was approximated to that of a circular pipe flow. Localized turbulent puffs, that is, axial uni-directional intermittencies similar to those observed in the transitional circular pipe flow, were observed in the annular Couette–Poiseuille flow. Puff splitting events were clearly observed rather far from the global critical Reynolds number, near which given puffs survived without a splitting event throughout the observation period, which was as long as 104 outer time units. The characterization as a directed-percolation universal class was also discussed.

Dynamics and proliferation of turbulent stripes in plane-Poiseuille and plane-Couette flows

“…Finally, we would like to briefly mention recent studies in Couette–Poiseuille flow (Klotz et al. 2017; Morimatsu & Tsukahara 2020; Klotz et al. 2021; Liu et al.…”

“…Finally, we would like to briefly mention recent studies in Couette-Poiseuille flow (Klotz et al 2017;Morimatsu & Tsukahara 2020;Klotz et al 2021;Liu et al 2021;Shuai, Liu & Gayme 2022), a geometry that allows us to link the two flows studied here. Future studies in this geometry could investigate the nature of stripes for increasing pressure driving, i.e.…”

Intermittency in Transitional Shear Flows

“…A series of careful direct numerical studies explore the dynamics of individual coherent structures at the onset of turbulence, in possible connection with the directed percolation regime expected theoretically. Morimatsu and Tsukahara [6] focus on the mechanisms leading localized turbulent structures in annular Couette-Poiseuille flow to split into two. Takeda et al [7] verify the existence of a critical range of annular Couette flow using artificial extensions of numerical domains.…”