The onset of centrifugal instability in an open cavity flow

This study deals with the experimental investigation of the onset of instability in an open cavity flow, in the incompressible limit. Far below the development of self-sustained oscillations, the first instability is three-dimensional on the inner recirculating flow. We address the case of a cavity of a large span-wise aspect ratio in which the side-wall effects are negligible. We study the pattern selection at threshold as the stream-wise aspect ratio is varied and, for large aspect ratios, we report the development of a second mode, which is quasi-symmetric to the primary mode.