Pictures of the vorticity of 2D Navier-Stokes equations

Streamline patterns with different Reynolds numbers

Streamline patterns of different, mode-3 solutions with the same Reynolds numbers

Streamline patterns of mode-2 solutions with different Reynolds numbers

Stationary Navier-Stokes flow in 2D torus, the graph of the derivative of the vorticity, the aspect ratio is 0.7

Stationary Navier-Stokes flow in 2D torus, the graph of the the derivative of the vorticity, the aspect ratio is 0.999

Computational data

Reynolds number = 20000.0, aspect ratio = 0.70
Reynolds number = 10000.0, aspect ratio = 0.999

See my paper " A Study of Bifurcation of Kolmogorov Flows with an Emphasis on the Singular Limit, Doc.Math.J.DMV Extra Volume III, (1998), pp. 513--522, which you can download from internet