Concept

Vortex-induced vibration

Publications associées (28)

Coexistence of Active and Hydrodynamic Turbulence in Two-Dimensional Active Nematics

In active nematic liquid crystals, activity is able to drive chaotic spatiotemporal flows referred to as active turbulence. Active turbulence has been characterized through theoretical and experimental work as a low Reynolds number phenomenon. We show that ...

2022

Growth, timing, & trajectory of vortices behind a rotating plate

Diego Francescangeli

The presence of aerodynamic vortices is widespread in nature. They can be found at small scales near the wing tip of flying insects or at bigger scale in the form of hurricanes, cyclones or even galaxies. They are identified as coherent regions of high vor ...

EPFL2022

Scaling of the translational velocity of vortex rings behind conical objects

Karen Ann J Mulleners, Guillaume de Guyon-Crozier

Ring vortices are efficient at transporting fluid across long distances. They can be found in nature in various ways: they propel squids, inject blood in the heart, and entertain dolphins. These vortices are generally produced by ejecting a volume of fluid ...

2021

Homogenization-based design of microstructured membranes: wake flows past permeable shells

François Gallaire, Edouard Boujo, Pier Giuseppe Ledda, Giuseppe Antonio Zampogna

A formal framework to characterize and control/optimize the flow past permeable membranes by means of a homogenization approach is proposed and applied to the wake flow past a permeable cylindrical shell. From a macroscopic viewpoint, a Navier-like effecti ...

Cambridge University Press2021

Phenomenology and scaling of optimal flapping wing kinematics

Karen Ann J Mulleners, Alexander Gehrke

Biological flapping wing fliers operate efficiently and robustly in a wide range of flight conditions and are a great source of inspiration to engineers. The unsteady aerodynamics of flapping wing flight are dominated by large-scale vortical structures tha ...

IOP PUBLISHING LTD2021

Evolution of the vorticity distribution in vortex rings

Guillaume de Guyon-Crozier

Vortex rings are very efficient at transporting fluid on long distances and can generate large forces, either thrust or drag. These abilities are influenced by the vorticity distribution within the vortex. Previous work on vortices produced by piston-cylin ...

EPFL2021

Physical Mechanism and Flow Control of Tip Vortex Cavitation

Ali Amini

Occurrence of cavitation in hydraulic machines is a challenging issue because it is often accompanied with loss of efficiency, noise emissions, vibrations, and erosion damages. Tip vortices, in particular, are an ideal site for the development of cavitatio ...

EPFL2020

Fundamental Applications of Nanopores: Controlled DNA Translocations to Nanofluidics

Sebastian James Davis

Nanopores are nanometer sized openings that are the connection between two electrolyte filled reservoirs. The measurement of the ion transport flowing through such a pore allows to probe physically or biologically interesting phenomena. These range from th ...

EPFL2020

Dynamic stall on an airfoil undergoing VAWT blade angle of attack variations

Karen Ann J Mulleners, Sébastien Le Fouest, Sabrina Henne

Vertical axis wind turbines have several attractive features in the context of energy production in urban areas, but the inherent aerodynamic complexity of the flow around them has challenged their development on a larger scale. They generally operate at l ...

2020

Coherent Structure Interaction During Unsteady Separation

Karen Ann J Mulleners

Unsteady flow separation in rotationally augmented flow fields plays a significant role in the aerodynamic performance of industrial rotors, including wind turbines. Current computational models underestimate the aerodynamic loads due to the inaccurate pre ...

2019

Mitigating tip vortex cavitation by a flexible trailing thread

Mohamed Farhat, Ali Amini

Tip Vortex Cavitation (TVC) is a major issue in design and operation of axial hydraulic machines. We investigate the capacity of a flexible trailing thread in alleviating TVC by analyzing the flow-induced motion. For this purpose, a nylon thread with three ...

AMER INST PHYSICS2019

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

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

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

Alfio Quarteroni, Michel Deville, 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

Cfd-Based Correlation For Forced Convection Heat Transfer In Circular Ducts Of Internally Heated Molten Salts

Carlo Fiorina

Heat transfer phenomena involving internally heated fluid flows are of particular interest in several industrial applications, in chemical plants as in the nuclear field. This topic is relevant for the development of the Molten Salt Reactors (MSRs) since i ...

AMER SOC MECHANICAL ENGINEERS2018

Distinct transition in flow statistics and vortex dynamics between low- and high-extent turbulent drag reduction in polymer fluids

Tobias Schneider

Flexible polymer additives are known to reduce the energy dissipation and friction drag in turbulent flows. As the fluid elasticity increases, the flow undergoes several stages of transitions. Much attention in the area has been focused on the onset of dra ...

2018

Apparatus for treating excess intraocular fluid

Nikolaos Stergiopoulos, Constantinos Stergiopulos

Apparatus and methods are provided for treating diseases that produce elevated intraocular pressures, such as glaucoma, wherein the device operates on the principles of a Starling resistor, and includes a housing, a deformable structure and a spring mounte ...

2017

SENSITIVITY ANALYSIS OF THE HYDROMORPHOLOGICAL INDEX OF DIVERSITY USING NUMERICAL GENERATED DATA

Anton Schleiss, Severin Stähly, Pierre Bourqui

River restoration has become a priority goal in many countries. The interest in rivers as valuable habitats for floral and faunal diversity and as an ecosystem with important functions has increased. For evaluating the structural changes from a river resto ...

2017

Unsteady fluid dynamics around a hovering flat plate wing

Swathi Badala Krishna

Insect flight is characterised by complex time-dependent flows in response to the unsteady wing movements. Biological fliers exploit the unsteady flow fields to modulate aerodynamic forces, thereby displaying unmatched flight performance, especially in hov ...

EPFL2017

Theoretical and numerical studies of atmospheric boundary-layer flows over complex terrain

Marco Giovanni Giometto

Atmospheric boundary-layer (ABL) flows over complex terrain have been the focus of active research, given their impact on weather and climate variability. Surface complexity is understood in a broad sense and includes variation in roughness properties, inc ...

EPFL2016