Generalized 3D Kolmogorov flow: effect of strong large-scale damping

Turbulent flows can be understood as the superposition of a mean flow, which evolves slowly and is shaped by boundaries or forcing mechanisms, and a multitude of chaotic, short-lived fluctuations. We performed pseudo-spectral simulations of a turbulent three-dimensional Kolmogorov flow with large-scale damping on an aspect-ratio-three domain, which is driven by a sinusoidal shearing body force. The visualization shows the vorticity averaged over the direction normal to the forcing plane to emphasize the large-scale counter-rotating vortices. The bottom plot shows an effective wavenumber of the large-scale state. For large values of the damping parameter, the only stable large-scale state is the three vortex-pair state, i.e. k_s = 1. Please see for further details.