Self-sustained oscillations of open cavity flows: when the inner flow dynamics couple to the shear-layer oscillations
Résumé
Open cavity flows are known to develop energetic
self-sustaining shear-layer oscillations. Such oscillations
are strongly modulated in time, as the result of nonlinear
feedback mechanisms and coupling with the dynamics of
inner-flow patterns. The latter result from centrifugal instabilities
that develop well-before the shear-layer start
oscillating. Depending on the cavity aspect ratio and its
span to depth ratio, a family of quasi-steady modes is selected
at threshold for small aspect ratio while a family of
left and right traveling modes is selected at large aspect
ratio, as predicted by linear stability analyses.