Publications associées à Estimating the non-dimensional energy of vortex rings by modelling their roll-up

Publications associées (29)

Reactive collision-free motion generation in joint space via dynamical systems and sampling-based MPC

Aude Billard, Nadia Barbara Figueroa Fernandez, Mikhail Koptev

Dynamical system (DS) based motion planning offers collision-free motion, with closed-loop reactivity thanks to their analytical expression. It ensures that obstacles are not penetrated by reshaping a nominal DS through matrix modulation, which is construc ...

Sage Publications Ltd2024

Strength and timing of primary and secondary vortices generated by a rotating plate

Karen Ann J Mulleners, Diego Francescangeli

Accurate predictions of how vortices grow, evolve, and separate from aerodynamic objects are desirable for various applications ranging from autonomous aerial vehicles to wind turbines. Here, we present an experimental characterisation of the formation pro ...

2023

Propagation of planar three-dimensional buoyant hydraulic fractures

Andreas Möri

Hydraulic fractures are driven by an internal fluid pressure exceeding the minimum compressive stress, propagating in a direction perpendicular to the latter. This class of tensile fractures has gained interest over the last fifty years due to the developm ...

EPFL2023

Mechanism balancing taxonomy

Simon Nessim Henein, Hubert Pierre-Marie Benoît Schneegans, Florent Cosandier

The balancing of mechanisms consists in distributing their moving masses, inertias, and elastic components in order to achieve key mechanical properties, such as the elimination of the shaking forces and moments exported onto their supporting structure or ...

2023

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

Lagrangian analysis of bio-inspired vortex ring formation

Karen Ann J Mulleners, Mrudhula Baskaran

Pulsatile jet propulsion is a highly energy-efficient swimming mode used by various species of aquatic animals that continues to inspire engineers of underwater vehicles. Here, we present a bio-inspired jet propulsor that combines the flexible hull of a je ...

2022

Effects of spanwise confinement on stratified shear instabilities

François Gallaire, Yves-Marie François Ducimetière

We consider the influence of transverse confinement on the instability properties of velocity and density distributions reminiscent of those pertaining to exchange flows in stratified inclined ducts, such as the recent experiment of Lefauve et al. [J. Flui ...

2021

Analytical Studies in Support of an Improved Approach to the Design of Acceleration-Sensitive Nonstructural Elements

Dimitrios Lignos, Ahmed Mohamed Ahmed Elkady

This paper summarizes a series of analytical studies that were conducted in connection with an improved approach for the design of acceleration-sensitive nonstructural elements. In the new approach, bracing to secure nonstructural elements to the structure ...

Applied Technology Council, Sponse2022

Stabilization of the linearized water tank system

Shengquan Xiang

In this article we study the so-called water tank system. In this system, the behavior of water contained in a 1-D tank is modelled by Saint-Venant equations, with a scalar distributed control. It is well-known that the linearized systems around uniform st ...

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

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

Angular Momentum in Rotating Superfluid Droplets

Christoph Bostedt, Camila Bacellar Cases Da Silveira

The angular momentum of rotating superfluid droplets originates from quantized vortices and capillary waves, the interplay between which remains to be uncovered. Here, the rotation of isolated submicrometer superfluid He-4 droplets is studied by ultrafast ...

AMER PHYSICAL SOC2020

Continuously-fed density currents over impermeable and porous substrates

Sara Venuleo

Gravity currents are buoyancy-driven flows having a significant impact on the environment and human life. They can be observed in a vast range of natural and anthropogenic scenarios, such as seawater and freshwater, the atmosphere, or industrial processes. ...

EPFL2020

Swirl number based transposition of flow-induced mechanical stresses from reduced scale to full-size Francis turbine runners

François Avellan, Arthur Tristan Favrel, Christian Landry, Joao Gomes Pereira Junior, Keita Yamamoto

At part load conditions, Francis turbines are subject to the emergence of a hydrodynamic instability in their draft tube, referred to as precessing vortex rope. It induces pressure pulsations in the water passages at the precession frequency of the vortex, ...

2020

LES investigation of the influence of cavitation on flow patterns in a confined tip-leakage flow

Mohamed Farhat

In the present paper, Large Eddy Simulations combined with the Zwart-Gerber-Belamri cavitation model are conducted to study the flow characteristics in a tip-leakage flow. A reasonable agreement is obtained between the numerical and experimental data. With ...

PERGAMON-ELSEVIER SCIENCE LTD2019

Particle transport at arbitrary timescales with Poisson-distributed collisions

Ambrogio Fasoli, Ivo Furno, Paolo Ricci, Marcelo Baquero Ruiz, Fabian Manke

We develop a model to investigate the time evolution of the mean location and variance of a random walker subject to Poisson-distributed collisions at constant rate. The collisions are instantaneous velocity changes where a new value of velocity is generat ...

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

Data-driven Measurement Designs for Magnetic Resonance Imaging

Baran Gözcü

Despite being a powerful medical imaging technique which does not emit any ionizing radiation, magnetic resonance imaging (MRI) always had the major problem of long scanning times that can take up to an hour depending on the application. It also requires u ...

EPFL2019

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

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