GALLAIRE , Francois

A separated boundary layer flow at the rear of a bump is considered and two-dimensional flow states at increasing Reynolds numbers are computed using a nonlinear continuation procedure for the stationary Navier-Stokes system. The global instability analysis of the steady states is performed by computing two-dimensional temporal modes. The...

A separated boundary-layer flow at the rear of a bump is considered. The flow undergoes two-dimensional low-frequency global oscillations known as 'flapping' typical for elongated separation bubbles. Computing equilibrium stationary states of the Navier-Stokes equations and performing a global instability analysis, the onset of the...

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A separated boundary layer flow at the rear of a bump is considered and two-dimensional flow states at increasing Reynolds numbers are computed using a nonlinear continuation procedure for the stationary Navier-Stokes system. The global instability analysis of the steady states is performed by computing two-dimensional temporal modes. The...

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The possibility of model reduction using global modes is readdressed, aiming at the controlling of a globally unstable separation bubble induced by a bump geometry. A combined oblique and orthogonal projection approach is proposed to design an estimator and controller in a Riccati-type feedback setting. An input-output criterion is used to...

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Une couche limite décollée instable est considérée, le décollement étant induit par une bosse montée sur une plaque plane. L'instabilité de la zone de recirculation fait apparaître un battement à basse fréquence, connu sous le nom de "flapping". Cette instabilité bidimensionnelle peut être décrite par une superposition de modes globaux...

International audience

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We analyse the force balance on a cylindrical drop in a Hele-Shaw cell, subjected to a Marangoni flow caused by a surface tension gradient. Depth-averaged Stokes equations, called Brinkman equations, are introduced and a general closed form solution is obtained. The validity of the averaging procedure is ascertained by considering a linear...

When transported in confined geometries rigid fibers show interesting transport dynamics induced by friction with the top and bottom walls. Fiber flexibility causes an additional coupling between fiber deformation and transport and is expected to lead to more complex dynamics. A first crucial step for their understanding is the characterization...