Secondary instability of centrifugal vortices in a cavity shear flow

We are interested in the development of centrifugal instabilities in an open cavity flow. Several works deal with cavity flows but very often these studies concern the shear layer and the acoustic of that two dimensional instability. We present here the development of a three dimensional instability, resulting in Taylor-Görtler-like vortices which are created by the curvature of the recirculation and its confinement by the walls. This primary instability manifests itself in the form of pairs of counter-rotating tori and the dynamic of these structures depends on experimental parameters- Reynolds number based on the cavity depth and the aspect ratio. For distinctive values of parameters, that primary instability exhibits a spanwise drift. A parametric study has been realized with flow visualization [1] and revealed, for dif-ferent parameters, a secondary instability. In flow visualizations, that instability shows axial movement out of phase between vortices of the same pair. We want to characterize quantitatively this secondary instability. For that purpose, we study a case with the secondary instability and its spanwise drift. In order to detect the vortices and to characterize their behaviors, Particle Image Velocimetry (PIV) measurements have been carried out. PIV fields are obtained with an optical flow algorithm [2]. Thi