Dynamics of reversals and condensates in two-dimensional Kolmogorov flows

Mishra, Pankaj Kumar ; Herault, Johann ; Fauve, Stephan ; Verma, Mahendra K. (2015) Dynamics of reversals and condensates in two-dimensional Kolmogorov flows Physical Review E - Statistical, Nonlinear and Soft Matter Physics, 91 (5). ISSN 1539-3755

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Official URL: http://doi.org/10.1103/PhysRevE.91.053005

Related URL: http://dx.doi.org/10.1103/PhysRevE.91.053005

Abstract

We present numerical simulations of the different two-dimensional flow regimes generated by a constant spatially periodic forcing balanced by viscous dissipation and large-scale drag with a dimensionless damping rate 1 / Rh . The linear response to the forcing is a 6 × 6 square array of counterrotating vortices, which is stable when the Reynolds number Re or Rh are small. After identifying the sequence of bifurcations that lead to a spatially and temporally chaotic regime of the flow when Re and Rh are increased, we study the transitions between the different turbulent regimes observed for large Re by varying Rh . A large-scale circulation at the box size (the condensate state) is the dominant mode in the limit of vanishing large-scale drag ( Rh large). When Rh is decreased, the condensate becomes unstable and a regime with random reversals between two large-scale circulations of opposite signs is generated. It involves a bimodal probability density function of the large-scale velocity that continuously bifurcates to a Gaussian distribution when Rh is decreased further.

Item Type:Article
Source:Copyright of this article belongs to The American Physical Society.
ID Code:118940
Deposited On:05 Jun 2021 04:12
Last Modified:05 Jun 2021 04:12

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