Publications related to Sensitivity of stochastic perturbations in a noise amplifier flow

Generalized impedance boundary conditions for strongly absorbing obstacle: The full wave equation

This paper is devoted to the study of the generalized impedance boundary conditions (GIBCs) for a strongly absorbing obstacle in the time regime in two and three dimensions. The GIBCs in the time domain are heuristically derived from the corresponding cond ...

World Scientific Publishing2015

Experiments of flow separation at the inner bank of open-channel bends

Anton Schleiss, Koen Blanckaert, Joris Heyman

In spite of its hydraulic and morphologic importance, the conditions of occurrence of flow separation at the inner bank of open channel bends are still not known. In a series of 23 experiments in a laboratory open channel bend with flat sand bed, it was in ...

2015

An adjoint-based approach to the optimal control of separated flows

Edouard Boujo

Flow separation is relevant to many industrial applications, since it is detrimental to the aerodynamic performance of vehicles, induces vibrations in mechanical structures, but can also contribute to improve mixing in combustion devices. In this thesis, t ...

EPFL2014

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 desta ...

Elsevier France-Editions Scientifiques Medicales Elsevier2014

Linear response to harmonic forcing of the non-parallel Batchelor vortex

François Gallaire, Francesco Viola, Cristobal Manuel Arratia Martinez

The Batchelor vortex1 is a slowly developing asymptotic solution of the flow of a trailing line vortex. This flow has been comprehensively studied in its parallel approximation. In particular, the convective/absolute nature of the instability has been inve ...

2014

On the Connection between the Hamilton-Jacobi-Bellman and the Fokker-Planck Control Frameworks

Fabio Nobile

In the framework of stochastic processes, the connection between the dynamic programming scheme given by the Hamilton-Jacobi-Bellman equation and a recently proposed control approach based on the Fokker-Planck equation is discussed. Under appropriate assum ...

2014

Distributed Measurement of Signal Power Evolution in a Phase Sensitive Parametric Amplifier

Luc Thévenaz, Camille Sophie Brès, Marcelo Alfonso Soto Hernandez, Fatemeh Alishahi, Andrey Denisov

A method to measure the signal power evolution along phase-sensitive parametric amplifiers is proposed using Brillouin optical time-domain analysis. Different evolutions along the fiber are reported by varying input wave phases, including amplification and ...

OSA2014

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

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

Sensitivity of stochastic perturbations in a noise amplifier flow

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Generalized impedance boundary conditions for strongly absorbing obstacle: The full wave equation

Experiments of flow separation at the inner bank of open-channel bends

An adjoint-based approach to the optimal control of separated flows

Open-loop control of a separated boundary layer

Linear response to harmonic forcing of the non-parallel Batchelor vortex

On the Connection between the Hamilton-Jacobi-Bellman and the Fokker-Planck Control Frameworks

Distributed Measurement of Signal Power Evolution in a Phase Sensitive Parametric Amplifier

Open-loop control of noise amplification in separated boundary layers

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

Open-loop control of a separated boundary layer

Linear response to harmonic forcing of the non-parallel Batchelor vortex

Open-loop control of a separated boundary layer

Open-loop control of noise amplification in separated boundary layers

Generalized impedance boundary conditions for strongly absorbing obstacle: The full wave equation

Distributed Measurement of Signal Power Evolution in a Phase Sensitive Parametric Amplifier

Experiments of flow separation at the inner bank of open-channel bends

On the Connection between the Hamilton-Jacobi-Bellman and the Fokker-Planck Control Frameworks

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

Open-loop control of a separated boundary layer

An adjoint-based approach to the optimal control of separated flows