Lagrangian topologies for S = 0 and different combinations of $Re$ and $Str$ as indicated. The stroboscopic projection is carried out for $K≤1000$ and $ϕ0=0$⁠. Black and magenta dots indicate regular trajectories, while gray dots indicate chaotic trajectories. Blue lines in (g) are streamlines of the velocity field at $ϕ=0$⁠. For regular trajectories near the bottom of the cavity $y=−0.5$⁠, only every 20th to 100th intersection with the stroboscopic plane is plotted. (a) Str = 1, Re = 1, (b) Str = 1, Re = 10, (c) Str = 1, Re = 500, (d) Str = 0.05, Re = 1, (e) Str = 0.05, Re = 10, (f) Str = 0.05, Re = 500, (g) Str = 0.01, Re = 1, (h) Str = 0.01, Re = 10, and (i) Str = 0.01, Re = 500. (a) and (g) are reproduced with permission from L. Babor and H. C. Kuhlmann, Proc. Appl. Math. Mech. 20, e202000194 (2021). Copyright 2021 Authors, licensed under a Creative Commons Attribution Licence.