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François Gallaire

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Related publications (155)

The Hydrodynamics of a Micro-Rocket Propelled by a Deformable Bubble

François Gallaire, Giacomo Gallino, Lailai Zhu

We perform simulations to study the hydrodynamics of a conical-shaped swimming micro-robot that ejects catalytically produced bubbles from its inside. We underline the nontrivial dependency of the swimming velocity on the bubble deformability and on the ge ...

2019

Transport of flexible fibers in confined microchannels

François Gallaire, Jean Cappello, Mathias Simon Daniel Bechert

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 m ...

2019

Self-consistent triple decomposition of the turbulent flow over a backward-facing step under finite amplitude harmonic forcing

François Gallaire, Philippe Meliga, Eunok Yim

We investigate the saturation of harmonically forced disturbances in the turbulent flow over a backward-facing step subjected to a finite amplitude forcing. The analysis relies on a triple decomposition of the unsteady flow into mean, coherent and incohere ...

ROYAL SOC2019

Dripping down the rivulet

Gioele Mariano Nicolò Balestra, François Gallaire, Gaëtan Pierre Clément Lerisson, Pier Giuseppe Ledda

This paper is associated with a video winner of a 2018 American Physical Society's Division of Fluid Dynamics (DFD) Milton van Dyke Award for work presented at the DFD Gallery of Fluid Motion. ...

2019

Second-order sensitivity in the cylinder wake: Optimal spanwise-periodic wall actuation and wall deformation

François Gallaire, Edouard Boujo, Andrea Fani

Two-dimensional (2D) flows can be controlled efficiently using spanwise "waviness," i.e., a control (e.g., wall blowing and suction or wall deformation) that is periodic in the spanwise direction. This study tackles the global linear stability of 2D flows ...

AMER PHYSICAL SOC2019

Unraveling radial dependency effects in fiber thermal drawing

François Gallaire, Fabien Sorin, Alexis Gérald Page, Mathias Simon Daniel Bechert

Fiber-based devices with advanced functionalities are emerging as promising solutions for various applications in flexible electronics and bioengineering. Multimaterial thermal drawing, in particular, has attracted strong interest for its ability to genera ...

2019

Optimal Control of Part Load Vortex Rope in Francis Turbines

François Avellan, Simon Pasche, François Gallaire

The mitigation of the precessing vortex core developing in the draft tube of Francis turbines operating under part load conditions is crucial to increase the operation flexibility of these hydraulic machines to balance the massive power production of inter ...

ASME2019

Flow dynamics of a dandelion pappus: A linear stability approach

François Gallaire, Francesco Viola, Lorenzo Siconolfi, Pier Giuseppe Ledda

The study and control of flow instabilities is a key problem in aerodynamics. Aircrafts are designed not only to generate the lift force needed to balance their weight but, more importantly, to be stable and reasonably steady when in cruise conditions. Sim ...

2019

Hydrodynamic loading of perforated disks in creeping flows

François Gallaire, Lorenzo Siconolfi, Pedro Miguel Nunes Pereira de Almeida Reis, Matteo Pezzulla

We present results from an experimental investigation of a viscous fluid driven through and around porous disks at low and moderate Reynolds number conditions: Re = O(10(-4)-10(-3)) and Re = O(1-10). Specifically, we quantify the hydrodynamic drag that the ...

AMER PHYSICAL SOC2019

Controlling transport dynamics of confined asymmetric fibers

François Gallaire, Jean Cappello, Mathias Simon Daniel Bechert

Transport properties of particles in confining geometries show very specific characteristics as lateral drift, oscillatory movement between lateral walls or the deformation of flexible fibers. These dynamics result from viscous friction with transversal an ...

IOP Publishing - EPL Association2019

Film thickness distribution in gravity-driven pancake-shaped droplets rising in a Hele-Shaw cell

Gioele Mariano Nicolò Balestra, François Gallaire, Isha Shukla, Lailai Zhu, Nicolas Igor Jacques Kofman

We study here experimentally, numerically and using a lubrication approach, the shape, velocity and lubrication film thickness distribution of a droplet rising in a vertical Hele-Shaw cell. The droplet is surrounded by a stationary immiscible fluid and mov ...

Cambridge University Press2019

Particle size selection in capillary instability of locally heated coaxial fiber

François Gallaire, Saviz Mowlavi, Isha Shukla, Pierre-Thomas Paul Brun

Harnessing fluidic instabilities to produce structures with robust and regular properties has recently emerged as a new fabrication paradigm. This approach is exemplified in the work of Gumennik et al. [Nat. Commun. 4, 2216 (2103)], in which the authors fa ...

AMER PHYSICAL SOC2019

Absolute/convective secondary instabilities and the role of confinement in free shear layers

François Gallaire, Saviz Mowlavi, Cristobal Manuel Arratia Martinez

We study the linear spatiotemporal stability of an infinite row of equal point vortices under symmetric confinement between parallel walls. These rows of vortices serve to model the secondary instability leading to the merging of consecutive (Kelvin-Helmho ...

2018

Physics of Bubble-Propelled Microrockets

François Gallaire, Giacomo Gallino

A popular method to induce synthetic propulsion at the microscale is to use the forces created by surface-produced gas bubbles inside the asymmetric body of a catalytic swimmer (referred to in the literature as microrocket). Gas bubbles nucleate and grow w ...

2018

Rayleigh-Taylor instability under a spherical substrate

Gioele Mariano Nicolò Balestra, François Gallaire, David Minh-Phuc Nguyen

We investigate the Rayleigh-Taylor instability of a thin viscous film coating the inside of a spherical substrate. The aim of this work is to find and characterize the instability pattern in this spherical geometry. In contrast to the Rayleigh-Taylor insta ...

2018

Inertial manipulation of bubbles in rectangular microfluidic channels

Demetri Psaltis, Gioele Mariano Nicolò Balestra, François Gallaire, Seyyed Mohammad Hosseini Hashemi, Miguel Antonio Modestino, Lailai Zhu, Pooria Hadikhani

Inertial microfluidics is an active field of research that deals with crossflow positioning of the suspended entities in microflows. Until now, the majority of the studies have focused on the behavior of rigid particles in order to provide guidelines for m ...

2018

Predictive control of spiral vortex breakdown

François Avellan, Simon Pasche, François Gallaire

The predictive control of the self-sustained single spiral vortex breakdown mode is addressed in the three-dimensional flow geometry of Ruith et al. (2003) for a constant swirl number S = 1.095. Based on adjoint optimization algorithms, two different contr ...

Cambridge University Press2018

Edge states control droplet breakup in subcritical extensional flows

François Gallaire, Giacomo Gallino, Tobias Schneider

A fluid droplet suspended in an extensional flow of moderate intensity may break into pieces, depending on the amplitude of the initial droplet deformation. In subcritical uniaxial extensional flow the nonbreaking base state is linearly stable, implying th ...

2018

Viscous growth and rebound of a bubble near a rigid surface

François Gallaire, Giacomo Gallino

Motivated by the dynamics of microbubbles near catalytic surfaces in bubble-powered microrockets, we consider theoretically the growth of a free spherical bubble near a flat no-slip surface in a Stokes flow. The flow at the bubble surface is characterised ...

Cambridge University Press2018

Capillary hysteresis in sloshing dynamics: aweakly nonlinear analysis

François Gallaire, Francesco Viola, Pierre-Thomas Paul Brun

Cambridge University Press2018

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