When open flows pass an open cavity, it is known that for medium or large Reynolds
numbers, self-sustained oscillations generally appear. When more than one mode is
excited, some nonlinear competition between modes may occur. In the configuration
investigated here, the underlying dynamics are mainly driven by two dominant modes. The
interplay between these two modes is investigated using phase portraits, Poincaré sections,
and return maps. The toroidal structure of the phase portrait is then investigated using a …