Dynamics of reversals and condensates in two-dimensional Kolmogorov flows

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