Left, top panel: selected continuation curves in Rm of SN_2m at fixed Re; bottom panel: selected continuation curves in Re at fixed Rm. Right: existence boundary of SN_2m in the (Re, Rm) plane (blue/dashed line) obtained by interpolating the different saddle node points Rm_c(Re) and Re_c(Rm) (blue bullets). The orange area shows the domain of existence of SN_2m in parameter space. The red bullet shows a saddle note bifurcation point computed at double resolution (96 × 96 × 144).