Publications associées à Free surface

Stability of a liquid layer draining around a horizontal cylinder: Interplay of capillary and gravity forces

François Gallaire, Shahab Eghbali, Simeon Vladimirov Djambov

We study the drainage of a viscous liquid film coating the outside of a solid horizontal cylinder, where gravity acts vertically. We focus on the limit of large Ohnesorge numbers Oh, where inertia is negligible compared to viscous effects. We first study t ...

Amer Physical Soc2024

Swirling against the forcing: Evidence of stable counterdirected sloshing waves in orbital-shaken reservoirs

François Gallaire, Alessandro Bongarzone, Alice Evelyne Julienne Marcotte

We investigate the response of the free liquid surface in a partially filled circular cylindrical container undergoing a planar elliptic and time-periodic orbit while maintaining fixed its orientation. For small forcing amplitudes and deep liquid layers, w ...

Amer Physical Soc2023

Columnlike free-interface flows: symmetry breaking and linear instability

Shahab Eghbali

This thesis is dedicated to the analysis of a subclass of interfacial flows, columnlike free-interface flows, from two view angles: (i) the symmetry breaking under geometry-induced or external forces, (ii) their stability against infinitesimal disturbances ...

EPFL2023

From coating flow patterns to porous body wake dynamics via multiscale models

Pier Giuseppe Ledda

Multiscale phenomena are involved in countless problems in fluid mechanics. Coating flows are known to exhibit a broad variety of patterns, such as wine tears in a glass and dripping of fresh paint applied on a wall. Coating flows are typically modeled und ...

EPFL2022

Imaging of Chemical Kinetics at the Water–Water Interface in a Free-Flowing Liquid Flat-Jet

Andreas Osterwalder, Bruno Credidio

We present chemical kinetics measurements of the luminol oxidation chemiluminescence (CL) reaction at the interface between two aqueous solutions, using liquid jet technology. Free-flowing liquid microjets are a relatively recent development that have foun ...

2022

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

Application of particle-based numerical analysis to the practical design of Pelton turbine

François Avellan, Siamak Alimirzazadeh, Takashi Kumashiro

For the design optimization of the Pelton turbine, it is highly demanded to investigate the flow inside the turbine casing, which includes the water jet from the nozzles, the interaction between the jet and rotating runner, and the flow ejected from the bu ...

IOP PUBLISHING LTD2021

Numerical simulation of sediment dynamics with free surface flows

Arwa Mrad

We present a numerical model for the simulation of 3D mono-dispersed sediment dynamics in a Newtonian flow with free surfaces. The physical model is a macroscopic model for the transport of sediment based on a sediment concentration with a single momentum ...

EPFL2021

Force Scaling Comparison of Transport Phenomena in Proton Exchange Membrane Fuel Cell Flow Channels

Mahbod Heidari

Liquid-gas two-phase flow in flow channels of proton exchange membrane (PEM) fuel cells has been investigated extensively in the literature; however, a comparison between the order of the magnitude of the forces occurring within the flow channels has not b ...

ASME2021

Hydrodynamic dead zone in multiphase geophysical flows impacting a rigid obstacle

Xingyue Li

When a gravity-driven solid-fluid mixture, such as those in geophysical flows, hits a wall-like rigid obstacle, a metastable jammed zone called hydrodynamic dead zone (HDZ) may emerge. The unjammed-jammed transition of HDZ, controlled by the intricate inte ...

2021

Air mediates the impact of a compliant hemisphere on a rigid smooth surface

John Martin Kolinski, Siqi Zheng

Fleeting contact between solids immersed in a fluid medium governs the response of critically important materials, from coffee to soil. Rapid impact of soft solids occurs in systems as diverse as car tires, soft robotic locomotion and suspensions, includin ...

2021

Scanning PIV of turbulent flows over and through rough porous beds using refractive index matching

Christophe Ancey, Gauthier Paul Daniel Marie Rousseau

This paper presents image velocimetry measurements on turbulent flows adjacent to a permeable bed made of randomly packed glass particles. For measuring flow velocities inside the bed, the refractive index of the glass particles was matched with that of th ...

SPRINGER2020

Oxygen diffusion through air–water free surfaces in a pump–turbine operating in condenser mode

François Avellan, Elena Vagnoni, Loïc Andolfatto, Pierre Leroy

The present research aims at understanding the mass transfer of air into water in a reversible pump turbine operating in condenser mode. In particular, the diffusion of oxygen through the water free-surface both in the vaneless gap between the impeller bla ...

2019

GPU-accelerated Pelton turbine simulation using finite volume particle method coupled with linear eddy viscosity models

François Avellan, Ebrahim Jahanbakhsh, Audrey Paulette Solange Maertens, Sebastián Camilo Leguizamón Sarmiento, Siamak Alimirzazadeh, Takashi Kumashiro

The numerical investigation of the unsteady flow patterns around a Pelton bucket can be helpful to improve the overall turbine efficiency by optimizing the bucket design based on identified loss mechanisms. Since the flow is highly turbulent, modeling the ...

IOP PUBLISHING LTD2019

A Numerical Model For The Simulation Of Shallow Laser Surface Melting

Marco Picasso, Alexandre Caboussat, Alexandre Masserey, Julien Hess

We present a multi-physics model for the approximation of the coupled system formed by the temperature-dependent Navier-Stokes equations with free surfaces. The main application is the industrial process of shallow laser surface melting (SLSM), for laser p ...

INT CENTER NUMERICAL METHODS ENGINEERING2019

3D Boundary Element Simulation of Droplet Dynamics in Microchannels: How Droplets Squeeze Through Constrictions and Move in Electric Fields

Simon Sebastian Schütz

Flows of fluids with free surfaces show complex dynamical behavior. Examples include effects like capillary surface waves, topological transitions such as droplet breakup and coalescence, or pattern formation in wetting and de-wetting dynamics. These compl ...

EPFL2018

A semi-Lagrangian splitting method for the numerical simulation of sediment transport with free surface flows

Marco Picasso, Alexandre Caboussat, Gilles Steiner, Arwa Mrad

We present a numerical model for the simulation of 3D poly-dispersed sediment transport in a Newtonian flow with free surfaces. The physical model is based on a mixture model for multiphase flows. The Navier-Stokes equations are coupled with the transport ...

PERGAMON-ELSEVIER SCIENCE LTD2018

Experimental investigation of the sloshing motion of the water free surface in the draft tube of a Francis turbine operating in synchronous condenser mode

François Avellan, Elena Vagnoni, Arthur Tristan Favrel, Loïc Andolfatto

Hydropower units may be required to operate in condenser mode to supply reactive power. In this operating mode, the water level in the turbine or pump-turbine is decreased below the runner by closing the guide vanes and injecting pressurized air. While ope ...

2018

Jetting from cavitation bubbles due to multiple shockwaves

Mohamed Farhat, Outi Supponen

We present experimental observations of microjets formed by cavitation microbubbles. An underwater electric discharge, applied beneath a flat free surface, produces a primary compression wave, which undergoes several phase inversions upon reflections from ...

AMER INST PHYSICS2018

Hydrodynamics of a periodically wind‑forced small and narrow stratified basin: a large‑eddy simulation experiment

Alfred Johny Wüest, Damien Bouffard, Hugo Nicolás Ulloa Sánchez, Oscar Rodrigo Sepúlveda Steiner, Serban George Constantinescu, Kyoung Sik Chang

We report novel results of a numerical experiment designed for examining the basin-scale hydrodynamics that control the mass, momentum, and energy distribution in a daily wind-forced, small thermally-stratified basin. For this purpose, the 3-D Boussinesq e ...

2018