Plane Couette flow -- Transition at Re = 500

Plane Couette flow simulated on personal Fortran code.
Parameters are: Re=500; streamwise periodicity: 32*pi; spanwise periodicity: 16*pi.
Initial condition: circular perturbation from the laminar flow (visible after the first few time-steps) of order 1e-4.
Shown: streamwise velocity in the mid-plane between the walls. The colorbar spans velocities in [-0.6;0.6]. The streamwise (resp. spanwise) direction is shown on the x- (resp. z-)axis.
Every second on the video corresponds to 5 time units.