Publications associées à Effect of trailing edge shape on hydrodynamic damping for a hydrofoil

Noise-induced transitions past the onset of a steady symmetry-breaking bifurcation: The case of the sudden expansion

François Gallaire, Edouard Boujo, Yves-Marie François Ducimetière

We consider fluid flows, governed by the Navier-Stokes equations, subject to a steady symmetry-breaking bifurcation and forced by a weak noise acting on a slow timescale. By generalizing the multiple-scale weakly nonlinear expansion technique employed in t ...

2024

Vortex shedding from a composite hydrofoil: Experimental evidence of a novel "partial lock-in"

Mohamed Farhat, Qin Wu, Thomas Antoine Nicolas Berger, Yunqing Liu

Lock-in is of great importance in many engineering applications due to its practical implications for structural safety. The influence of composite bend-twist coupling on the wake dynamics and vortex-induced vibration around a carbon fiber composite hydrof ...

Aip Publishing2023

The effects of kinematics, flexibility, and planform on the vortex formation and aerodynamic performance of flapping wing flight

Alexander Gehrke

In this thesis, the aerodynamic challenges in flapping wing flight are addressed. In particular, the effects of different wing kinematics, flexibilities, and planforms on the the leading edge vortex development and aerodynamic performance are investigated. ...

EPFL2023

Numerical analysis of apparatus-induced dispersion for density-dependent solute transport in porous media

David Andrew Barry, Hong Zhang

The effects of apparatus-induced dispersion on nonuniform, density-dependent flow in a cylindrical soil column were investigated using a finite-element model. To validate the model, the results with an analytical solution and laboratory column test data we ...

2023

Visualization and modelling of dynamic flow in fibrous preforms for liquid composite molding

Helena Luisa Teixido Pedarros

Nowadays, Liquid Composite Molding techniques are often used to manufacture high quality fiber reinforced composite parts at a relatively low cost. These involve an infiltration process, in which a liquid resin is forced to ingress into a dry fibrous porou ...

EPFL2023

Experimental quantification of unsteady leading-edge flow separation

Karen Ann J Mulleners, Julien Dominique Claude Deparday

We propose here a method to experimentally quantify unsteady leading-edge flow separation on aerofoils with finite thickness. The methodology relies on the computation of a leading-edge suction parameter based on measured values of the partial circulation ...

Cambridge University Press2022

Weakly nonlinear evolution of stochastically driven non-normal systems

François Gallaire, Edouard Boujo, Yves-Marie François Ducimetière

We consider nonlinear dynamical systems driven by stochastic forcing. It has been largely evidenced in the literature that the linear response of non-normal systems (e.g. fluid flows) may exhibit a large variance amplification, even in a linearly stable re ...

Cambridge University Press2022

Automated flow control of a multi-lane swimming chamber for small fishes indicates species-specific sensitivity to experimental protocols

In fishes, swimming performance is considered an important metric to measure fitness, dispersal and migratory abilities. The swimming performance of individual larval fishes is often integrated into models to make inferences on how environmental parameters ...

2021

Nonlinear kinetic simulation study of the ion-ion streaming instability in single- and multi-ion species plasmas

Stephan Brunner

The nonlinear evolution of the ion-ion streaming instability (IISI) is studied using numerical techniques novel to this problem that afford direct insight into the evolution of the particle distributions of each species. During the linear phase of the inst ...

2021

The dynamics and timescales of static stall

Sébastien Le Fouest, Karen Ann J Mulleners, Julien Dominique Claude Deparday

Airfoil stall plays a central role in the design of safe and efficient lifting surfaces. We typically distinguish between static and dynamic stall based on the unsteady rate of change of an airfoil’s angle of attack. Despite the somewhat misleading denotat ...

2021

Ultrasonic Doppler flow velocity measurements as a co-indicator for the eco-morphological assessment in a residual flow reach

Giovanni De Cesare, Christian Mörtl, Robin Schroff

It is a complex task to evaluate the effects of a river rehabilitation measure on the riverscape’s habitat mosaic. This study investigated the medium term effects of a rehabilitation measure in a residual flow reach downstream of a hydroelectric dam. The r ...

ETH2021

A bioinspired Separated Flow wing provides turbulence resilience and aerodynamic efficiency for miniature drones

Stefano Mintchev, Matteo Di Luca

Small-scale drones have enough sensing and computing power to find use across a growing number of applications. However, flying in the low-Reynolds number regime remains challenging. High sensitivity to atmospheric turbulence compromises vehicle stability ...

AMER ASSOC ADVANCEMENT SCIENCE2020

Stall Delay and Leading-Edge Suction for a Pitching Airfoil with Trailing-Edge Flap

Karen Ann J Mulleners, Julien Dominique Claude Deparday, Guosheng He

The flow around a pitching NACA0015 airfoil with an oscillating trailing-edge flap is experimentally investigated to characterize the influence of the flap kinematics on the development of dynamic stall. We specifically focus on the timing of the stall dev ...

2020

Evaluation of a Dynamic Transfer Matrix for a Hydraulic Turbine

François Avellan, Andres Müller, Keita Yamamoto

It is well known that hydraulic machines experience various types of flow instabilities causing a negative influence on the system under off-design operations. The transfer matrix method correlating the flow properties in upstream and downstream of hydraul ...

2020

Continuously-fed gravity currents propagating over a finite porous substrate

Anton Schleiss, Mário Jorge Rodrigues Pereira Da Franca, Sara Venuleo

We present the results of laboratory investigations of continuously-fed density currents that propagate first over a smooth horizontal bed and then over a porous substrate of limited length. Inflow discharge, initial excess density, and substrate porositie ...

2019

Turbulent Flows over Rough Permeable Beds in Mountain Rivers: Experimental Insights and Modeling

Gauthier Paul Daniel Marie Rousseau

Steep mountain streams exhibit shallow waters with roughness elements such as stones and pebbles that are comparable in size to flow depth. Owing to the difficulty in measuring fluid velocities at the interface, i.e., from the rough permeable bed to the fr ...

EPFL2019

Flow field in a reservoir subject to pumped-storage operation - in situ measurement and numerical modeling

Giovanni De Cesare, Anton Schleiss, Michael Müller

In pumped-storage reservoirs, turbulent kinetic energy input from plant operation can be considerably high. Flow velocities were measured by Acoustic Doppler Current Profilers near the intake/outlet structure to describe flow patterns induced by pumped-sto ...

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

Application of the Rosenbrock methods to the solution of unsteady 3D incompressible Navier-Stokes equations

Michel Deville, Alfio Quarteroni, Simone Deparis, Luca Pegolotti, Filippo Menghini

We consider the Rosenbrock methods, namely a family of methods for Differential Algebraic Equations, for the solution of the unsteady three-dimensional Navier-Stokes equations. These multistage schemes are attractive for non-linear problems because they ac ...

2018

Strategies for faster impregnation in melt thermoplastic resin transfer molding process

Damiano Salvatori

Continuous fiber thermoplastic composites are potential substitutes of steel in structural automotive components, since they combine fiber strength and rigidity with ductility, potential recyclability and low density of the thermoplastic (TP) matrix. Resin ...

EPFL2018