Publications by Francesco Viola

Subharmonic parametric instability in nearly brimful circular cylinders: a weakly nonlinear analysis

François Gallaire, Alessandro Bongarzone, Francesco Viola

In labscale Faraday experiments, meniscus waves respond harmonically to small-amplitude forcing without threshold, hence potentially cloaking the instability onset of parametric waves. Their suppression can be achieved by imposing a contact line pinned at ...

Cambridge University Press2022

Relaxation of capillary-gravity waves due to contact line nonlinearity: A projection method

François Gallaire, Alessandro Bongarzone, Francesco Viola

We present a physics-inspired mathematical model based on successive linear eigenmode projections to solve the relaxation of small-amplitude and two-dimensional viscous capillary-gravity waves with a phenomenological nonlinear contact line model. We show t ...

American Institute of Physics2021

Flow dynamics of a dandelion pappus: A linear stability approach

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

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

Capillary hysteresis in sloshing dynamics: aweakly nonlinear analysis

François Gallaire, Pierre-Thomas Paul Brun, Francesco Viola

Cambridge University Press2018

Parabolic RANS solver for low-computational-cost simulations of wind turbine wakes

Giacomo Valerio Iungo, Francesco Viola

2018

Suppression of von Karman vortex streets past porous rectangular cylinders

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

Although the stability properties of the wake past impervious bluff bodies have been widely examined in the literature, similar analyses regarding the flow around and through porous ones are still lacking. In this work, the effect of the porosity and perme ...

2018

Theoretical framework to analyze the combined effect of surface tension and viscosity on the damping rate of sloshing waves

François Gallaire, Francesco Viola

Gravity force, surface tension, oscillating boundary layers, viscous dissipation, static meniscus, contact angle hysteresis, and moving contact lines are typical features of sloshing dynamics. All these ingredients influence capillary-gravity waves in a co ...

AMER PHYSICAL SOC2018

Flow control of weakly non-parallel flows: application to trailing vortices

François Gallaire, Giacomo Valerio Iungo, Francesco Viola, Erica Pezzica

A general formulation is proposed to control the integral amplification factor of harmonic disturbances in weakly non-parallel amplifier flows. The sensitivity of the local spatial stability spectrum to a base-flow modification is first determined, general ...

Cambridge University Press2017

The viscous torsional pendulum

François Gallaire, Francesco Viola

A disk that is free to rotate about its axis and connected to a torsional spring behaves as a damped oscillator when twisted and released. The initial elastic energy is periodically turned to kinetic energy and it gets progressively dissipated by the visco ...

Academic Press Ltd- Elsevier Science Ltd2017

Sloshing in a Hele-Shaw cell: experiments and theory

François Gallaire, Francesco Viola, Benjamin Jérémy Dollet

The response of the free liquid surface in a Hele-Shaw cell subjected to a horizontal oscillation is investigated. We study the low-oscillation-amplitude regime and we show, by varying the fluid viscosity, nu, and the forcing frequency, omega, that the rat ...

Cambridge University Press2017