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Edouard Boujo

Related publications (32)

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Sensitivity of stochastic perturbations in a noise amplifier flow

François Gallaire, Edouard Boujo

It is a well-known fact that small-amplitude perturbations can be amplified in globally stable flows due to non-normal mechanisms. This leads in the time domain to the transient growth of some initial disturbances, and in the frequency domain to the amplif ...

2014

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We use adjoint-based gradients to analyze the sensitivity of the drag force on a square cylinder. At Re = 40, the flow settles down to a steady state. The quantity of interest in the adjoint formulation is the steady asymptotic value of drag reached after ...

Amer Inst Physics2014

Manipulating flow separation: sensitivity of stagnation points, separatrix angles and recirculation area to steady actuation

François Gallaire, Edouard Boujo

A variational technique is used to derive analytical expressions for the sensitivity of several topological indicators of flow separation to steady actuation. Considering the boundary layer flow above a wall-mounted bump, the six following representative q ...

Royal Soc2014

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The analysis of Strykowski & Sreenivasan (JFM, 1990) provides experimental evidence that a small control cylinder suitably positioned in the wake of a main cylinder can alter vortex shedding close to the instability threshold. This problem was addressed fr ...

2014

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2014

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We perform a second-order sensitivity analysis of the linear temporal stability of a parallel flow subject to small spanwise periodic modification. The need for a second-order analysis results from the fact that spanwise-periodic flow modifications have a ...

2014

Open-loop control of a separated boundary layer

François Gallaire, Edouard Boujo

Linear optimal gains

G_opt(\omega)

are computed for the separated boundary-layer flow past a two-dimensional bump in the subcritical regime. Very large values are found, making it possible for small-amplitude noise to be strongly amplified and to destabi ...

Cépaduès Editions2013

Open-loop control of noise amplification in separated boundary layers

François Gallaire, Edouard Boujo

Linear optimal gains are computed for the subcritical two-dimensional separated boundary-layer flow past a bump. Very large optimal gain values are found, making it possible for small-amplitude noise to be strongly amplified and to destabilize the flow. Th ...

2013

Forced reattachment in separated flows: a variational approach to recirculation length reduction

François Gallaire, Edouard Boujo

Sensitivity analysis is used to design an open-loop control for separated flows. The length of the recirculation region

l_c

is expressed as a cost functional, and its sensitivity to actuation is derived analytically. This analysis allows to identify regi ...

2013

Sensitivity of optimal gains in a detached boundary layer

François Gallaire, Edouard Boujo

The flow over a 2D bump at moderate Reynolds numbers is studied as a pro- totype of detached boundary layers. It is well known that such non-normal systems can exhibit large energy amplification even in their stable regime, as characterized by transient gr ...

2012

Open-loop control of a separated boundary layer

François Gallaire, Edouard Boujo

Linear optimal gains

G_opt(\omega)

Cépaduès Editions2013

Forced reattachment in separated flows: a variational approach to recirculation length reduction

François Gallaire, Edouard Boujo

Sensitivity analysis is used to design an open-loop control for separated flows. The length of the recirculation region

l_c

is expressed as a cost functional, and its sensitivity to actuation is derived analytically. This analysis allows to identify regi ...

2013