Figure 2

Partial bifurcation diagram for the simplified Atri model, Equations (23) with various values of ε and other parameter values as in Table 1. The pink (solid) curve shows the position of the unique equilibrium of the model. This equilibrium has two Hopf bifurcations (labelled HB), with the equilibrium being of saddle type for parameter values between the two Hopf bifurcations and being stable otherwise. The remaining curves show the maximum c-values attained by the periodic orbits created in the Hopf bifurcations, for three choices of ε, i.e. ε = 0 (layer problem), ε = 10^-4 and ε = 10^-2 on the black solid, red dashed and blue dotted curves, resp. (b) Enlargement of the marked rectangle in (a). Note that the left-most Hopf bifurcation in (a) is subcritical when ε = 0 but supercritical for all ε > 0.