Fig. 5.

Active nematics in weak confinement. (A) Active nematic in the regime where topological defects nucleate both in the interior and at the boundary; the $+1/2$ defects are predominantly aligned along the flow direction. (B) Time evolution of the number of $+1/2$ defects (magenta), $-1/2$ defects (blue), and the total topological charge (black). The total charge remains +1 except for short-time tracking errors. (C) Spatial map of the instantaneous flow field and vorticity (vorticity scale is $\mathrm{\Omega }$ = $\pm$0.27 ${\text{s}}^{-1}$). (D) Time evolution of the flow order parameter demonstrates that the circular flows with specific handedness persist for periods up to 10 min. The vertical line in B and D corresponds to the time in A and C. Confinement diameter is 400 $\mathrm{\mu }$m.