Stroboscopic projections to $ϕ0=0$ showing nested KAM tori around a central periodic trajectory $x(0)$ (blue dot). Subharmonic resonances are shown in magenta. The Reynolds and Strouhal numbers are indicated in the sub-captions and color-coded corresponding to the line color in Fig. 10. (a) Re = 5, Str = 0.1, (b) Re = 10, Str = 0.1, (c) Re = 20, Str = 0.1, (d) Re = 10, Str = 0.25, (e) Re = 20, Str = 0.25, and (f) Re = 29, Str = 0.25.