Fig. 3: Deterministic stripe expansion and streak creation.

a Consecutive positions of a stripe at \({\rm{Re}}=655\). The downstream tip moves at a constant velocity diagonally across the channel as indicated by the dashed blue line, and laminar fluid is entrained at a constant rate. b Below the critical point, at \({\rm{Re}}=620\), the tip initially moves with the same velocity as the stripe at \({\rm{Re}}=655\) but slows down in time and eventually the stripe decays. c Snapshots of the wall normal velocities in the region around the downstream tip of the stripe at \({\rm{Re}}=655\), obtained from DNS, showing a pair of streaks are created every  ≈ 18 advective time units. To more easily follow the addition of streaks, the streaks emerging in the first snapshot (t = 0, arbitrary time origin) are shown with an arrow in all the subsequent snapshots. d The time interval between the addition of successive streaks shown as a function of time for \({\rm{Re}}=655\).