Publications associées à Experimental investigation of surface roughness effect on a free-flight sphere in a Ludwieg tube

Lumped Drag Model Identification and Real-Time External Force Detection for Rotary-Wing Micro Aerial Vehicles

This work focuses on understanding and identifying the drag forces applied to a rotary-wing Micro Aerial Vehicle (MAV). We propose a lumped drag model that concisely describes the aerodynamical forces the MAV is subject to, with a minimal set of parameters ...

IEEE2024

Method for wind harvesting and wind rejection in flying drones

Dario Floreano, Victor Casas Rochel, Nathan Samuel Müller, Charalampos Vourtsis, William John Stewart

The present invention concerns a method of manoeuvring a vertical take-off and landing, unmanned aerial drone (100) comprising at least an aerodynamic surface (101), wherein, during a flight of the drone, the aerodynamic surface generates lift and/or drag ...

2024

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

Covariant formulation of relativistic mechanics

Miguel Alexandre Ribeiro Correia

Accretion disks surrounding compact objects, and other environmental factors, deviate satellites from geodetic motion. Unfortunately, setting up the equations of motion for such relativistic trajectories is not as simple as in Newtonian mechanics. The prin ...

American Physical Society2022

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

Sharp turning maneuvers with avian-inspired wing and tail morphing

Dario Floreano, Enrico Ajanic, Mir Alikhan Bin Mohammad Feroskhan, Valentin Wüest

Flight in dense environments, such as forests and cities requires drones to perform sharp turns. Although fixed-wing drones are aerodynamically and energetically more efficient than multicopters, they require a comparatively larger area to turn and thus ar ...

2022

Design of an intake and a thruster for an atmosphere-breathing electric propulsion system

Thomas Binderup Jensen, Francesco Romano

Challenging space missions include those at very low altitudes, where the atmosphere is the source of aerodynamic drag on the spacecraft, that finally defines the mission's lifetime, unless a way to compensate for it is provided. This environment is named ...

2022

Insect Inspired Self-Righting for Fixed-Wing Drones

Dario Floreano, Victor Casas Rochel, Charalampos Vourtsis, William John Stewart

Micro Aerial Vehicles (MAVs) are being used in a wide range of applications such as surveillance, reconnaissance, inspection, and search and rescue. However, due to their size and mission profiles, they are prone to tipping over, jeopardizing their operati ...

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

Accurate buoyancy and drag force models to predict particle segregation in vibrofluidized beds

Mehrdad Kiani Oshtorjani

The segregation of large intruders in an agitated granular system is of high practical relevance, yet the accurate modeling of the segregation (lift) force is challenging as a general formulation of a granular equivalent of a buoyancy force remains elusive ...

AMER PHYSICAL SOC2021

On the numerical simulation of a confined cavitating tip leakage vortex under geometrical and operational uncertainties

Mohamed Farhat

The effects of operational and geometrical uncertainties on Tip Leakage Vortex (TLV) characteristics are investigated in the current research. Geometrical uncertainties are comprised of manufacturing tolerances or gradual geometry degradation over the time ...

PERGAMON-ELSEVIER SCIENCE LTD2021

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

Pressure on obstacles induced by granular snow avalanches

Michael Lukas Kyburz

The increasing population and the consequential demand for dwelling and recreation areas lead to more frequent conflicts between humans and natural hazards. In mountainous regions snow avalanches are, therefore, still a major threat to humans and infrastru ...

EPFL2021

Deformation of porous flexible strip in low and moderate Reynolds number flows

François Gallaire, Pedro Miguel Nunes Pereira de Almeida Reis, Matteo Pezzulla

We present results from a combined experimental and numerical investigation of the fluid-structure interaction of cantilevered porous flexible strips, towed through a fluid bath. We characterize the steady-state deformation of the strips and their associat ...

AMER PHYSICAL SOC2020

Forces on buildings with openings and orientation in a steady post-tsunami free-surface flow

Anton Schleiss, Michael Pfister, Davide Wüthrich

Steady free-surface flows around buildings occurring during flood or tsunami events can produce major damages and a quantification of the post-peak forces is essential for safety and resilience of coastal structures. The loading process is highly affected ...

2020

Extended Windage Loss Models for Gas Bearing Supported Spindles Operated in Dense Gases

Jürg Alexander Schiffmann, Kévin Rosset

Generic models are proposed to evaluate the skin friction coefficient acting on enclosed rotating disks and cylinders under various flow regimes. In particular, a model taking into account the inner radius of the disk is developed. The models are compared ...

2020

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

Structural pre-conceptual design studies for an EU DEMO equatorial EC port plug and its port integration

René Chavan, Minh Quang Tran

For the EU DEMO Tokamak, Electron Cyclotron (EC) launching systems for plasma heating and stabilization are under development. Various concepts for the optical system are currently studied of which the Mid Steering Antenna (MSA) with a steering mirror at a ...

Elsevier2020

Programmable Aerodynamic Drag on Active Dimpled Cylinders

Pedro Miguel Nunes Pereira de Almeida Reis, Dong Yan, Mark Andrew Guttag

This study demonstrates that the aerodynamic drag profile of a patterned deformable cylinder at high Reynolds numbers can be programmed, on demand, by modifying its topography through pneumatic actuation. The samples used in the experiments comprise a rigi ...

WILEY-V C H VERLAG GMBH2019

Are Existing Monocular Computer Vision-Based 3D Motion Capture Approaches Ready for Deployment? A Methodological Study on the Example of Alpine Skiing

Pascal Fua, Helge Jochen Rhodin, Mirela Ostrek

In this study, we compared a monocular computer vision (MCV)-based approach with the golden standard for collecting kinematic data on ski tracks (i.e., video-based stereophotogrammetry) and assessed its deployment readiness for answering applied research q ...

2019