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François Gallaire

Cette personne a quitté l’EPFL

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Publications associées (151)

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Counterpropagating Rossby waves in confined plane wakes

François Gallaire

In the present work, we revisit the temporal and the spatio-temporal stability of confined plane wakes under the perspective of the counterpropagating Rossby waves (CRWs). Within the context of broken line velocity profiles, each vorticity discontinuity ca ...

American Institute of Physics2012

Interaction between counterpropagating Rossby waves and capillary waves in planar shear flows

François Gallaire

A counterintuitive destabilizing effect of the surface tension in planar wakes has been observed by Tammisola et al. ["Effect of surface tension on global modes of confined wake flows," Phys. Fluids 23, 014108 (2011)] and Biancofiore et al. ["Direct numeri ...

American Institute of Physics2015

Sensitivity of aerodynamic forces in laminar and turbulent flow past a square cylinder

François Gallaire, Edouard Boujo, Philippe Meliga

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 ...

2014

A unified criterion for the centrifugal instabilities of vortices and swirling jets

François Gallaire

Swirling jets and vortices can both be unstable to the centrifugal instability but with a different wavenumber selection: the most unstable perturbations for swirling jets in inviscid fluids have an infinite azimuthal wavenumber, whereas, for vortices, the ...

Cambridge University Press2013

Drops on the Underside of a Slightly Inclined Wet Substrate Move Too Fast to Grow

François Gallaire, Pierre-Thomas Paul Brun, Pier Giuseppe Ledda

Pendant drops suspended on the underside of a wet substrate are known to accumulate fluid from the surrounding thin liquid film, a process that often results in dripping. The growth of such drops is hastened by their ability to translate over an otherwise ...

AMER PHYSICAL SOC2021

Optimal spanwise-periodic control for recirculation length in a backward-facing step flow

François Gallaire, Edouard Boujo, Eunok Yim, Isha Shukla

Three-dimensional control is considered in the flow past a backward-facing step (BFS). The BFS flow at Reynolds number Re = 500 (defined with the step height and the maximum inlet velocity) is two-dimensional and linearly stable but increasingly receptive ...

AMER PHYSICAL SOC2020

Prediction of Self-Assembled Dewetted Nanostructures for Photonics Applications via a Continuum-Mechanics Framework

François Gallaire, Fabien Sorin, Pier Giuseppe Ledda, Louis Marie Philippe Martin-Monier, Pierre-Luc Eloi Piveteau

When a liquid film lies on a nonwettable substrate, the configuration is unstable, and the film spontaneously ruptures to form droplets. This phenomenon, known as dewetting, commonly leads to undesirable morphological changes. Nevertheless, recent works, c ...

American Physical Society (APS)2021

Foam on troubled water: Capillary induced finite-time arrest of sloshing waves

François Gallaire, Pierre-Thomas Paul Brun, Francesco Viola

Interfacial forces exceed gravitational forces on a scale small relative to the capillary length-two millimeters in the case of an air-water interface-and therefore dominate the physics of sub-millimetric systems. They are of paramount importance for vario ...

Amer Inst Physics2016

Self-consistent model for the saturation mechanism of the response to harmonic forcing in the backward-facing step flow

François Gallaire, Vladislav Mantic Lugo

Certain flows denominated as amplifiers arc characterized by their global linear stability while showing large linear amplifications to sustained perturbations. As the forcing amplitude increases, a strong saturation of the response appears when compared t ...

Cambridge University Press2016

Revisiting the drag reduction problem using adjoint-based distributed forcing of laminar and turbulent flows over a circular cylinder

François Gallaire, Edouard Boujo, Philippe Meliga

This study assesses the ability of a sensitivity-based, span-wise homogeneous control velocity distributed at the surface of a circular cylinder to cut down the cost of reducing drag by more classical techniques, e.g., base bleed and lateral suction. At Re ...

ELSEVIER SCIENCE BV2018

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

Coating thickness prediction for a viscous film on a rough plate

François Gallaire, John Martin Kolinski, Giuseppe Antonio Zampogna, Lebohang Molefe

Surface roughness significantly modifies the liquid film thickness entrained when dip coating a solid surface, particularly at low coating velocity. Using a homogenization approach, we present a predictive model for determining the liquid film thickness co ...

Cambridge University Press2024

Modified McCannel Iridoplasty Simulating Basal Iridectomy for Silicone Oil Tamponade in Aphakia and Partial Aniridia

Demetri Psaltis, François Gallaire

Georg Thieme Verlag2014

Feedback-free microfluidic oscillator with impinging jets

Philippe Renaud, François Gallaire, Arnaud Bertsch, Alessandro Bongarzone, Margaux Catherine Marie Duchamp

The present paper describes a microfluidic oscillator based on facing impinging jets and operating in laminar flow conditions. Using appropriate microchannel configurations, pulsatile liquid flows are generated at the microscale from steady and equal inlet ...

2020

Understanding the destabilizing role for surface tension in planar shear flows in terms of wave interaction

François Gallaire

Both surface tension and buoyancy force in stable stratification act to restore perturbed interfaces back to their initial positions. Hence, both are intuitively considered as stabilizing agents. Nevertheless, the Taylor-Caulfield instability is a countere ...

Amer Physical Soc2017

The influence of shear layer thickness on the stability of confined two-dimensional wakes

François Gallaire

The influence of confinement onto the inviscid and incompressible linear stability of the family of wakes introduced by Monkewitz [Phys. Fluids 31, 999 (1988)] is examined. The nondimensional parameters of the model, the velocity ratio Λ, defined as ratio ...

2011

Vortex-Breakdown-Induced Particle Capture in Branching Junctions

François Gallaire, Andrea Fani

We show experimentally that a flow-induced, Reynolds number-dependent particle-capture mechanism in branching junctions can be enhanced or eliminated by varying the junction angle. In addition, numerical simulations are used to show that the features respo ...

American Physical Society2016

Instability and trajectories of buoyancy-driven annular disks: A numerical study

François Gallaire, Pier Giuseppe Ledda

We investigate the stability of the steady vertical path and the emerging trajectories of a buoyancy -driven annular disk as the diameter of its central hole is varied. The steady and axisymmetric wake associated with the steady vertical path of the disk, ...

Amer Physical Soc2024

Lagrangian versus Eulerian view on the mean drift and streaming flows in orbital sloshing

François Gallaire, Alessandro Bongarzone

Orbital sloshing is a technique to gently mix a container's liquid content and it is commonly used in fermentation and cell cultivation processes. Besides the rich wave dynamics observed at the interface, Bouvard et al. [Phys. Rev. Fluids 2, 084801 (2017)2 ...

2024

Effects of incoming wind condition and wind turbine aerodynamics on the hub vortex instability

François Gallaire, Giacomo Valerio Iungo, Francesco Viola

Dynamics and instabilities occurring in the near-wake of wind turbines have a crucial role for the wake downstream evolution, and for the onset of far-wake instabilities. Furthermore, wake dynamics significantly affect the intra-wind farm wake flow, wake i ...

Iop Publishing Ltd2015