Pierre-Yves Passaggia

Wake transition of a rolling sphere

Graphical Abstract

Optimization and control of a separated boundary-layer flow

In order to investigate the possibilities of controlling wall-bounded ows, optimal control of the nonlinear dynamics of a separated boundary-layer ow is studied using a localized blowing-suction at the wall. Control laws are computed using a formulation based on the augmented Lagrangian approach using the full knowledge of the ow dynamics. The case study consists of a laminar separated boundary-layer ow over a bump.

Low-frequency beating and transverse instability of a laminar separated boundary-layer flow behind a bump

The instability behavior of a separated laminar boundary-layer ow over a shallow bump is investigated experimentally. This geometry generates an elongated recirculation bubble subject to a low-frequency apping. Previous numerical simulations have shown that, for this con guration, two instabilities coexist. The centrifugal instability of the recirculation bubble is rst investigated, then the low-frequency beating is compared with the two-dimensional instability observed in numerical simulations.