Publications associées à Effet Coandă

Understanding snow saltation parameterizations: lessons from theory, experiments and numerical simulations

Michael Lehning, Armin Sigmund, Daniela Brito Melo

Drifting and blowing snow are important features in polar and high mountain regions. They control the surface mass balance in windy conditions and influence sublimation of snow and ice surfaces. Despite their importance, model representations in weather an ...

2024

Numerical study on the scale effect of tip vortex cavitation induced by incoming velocities and scale ratios

Mohamed Farhat, Huaiyu Cheng, Mohan Xu

Large eddy simulations of tip vortex cavitation (TVC) around an elliptical hydrofoil is performed to study its scale effect. A satisfying agreement is obtained between the numerical and experimental data. It indicates that the scale effect of TVC is remark ...

PERGAMON-ELSEVIER SCIENCE LTD2023

Modeling snow saltation: the effect of grain size and interparticle cohesion

Michael Lehning, Varun Sharma, Armin Sigmund, Daniela Brito Melo, Francesco Comola

This dataset includes the parallel application and the main results supporting the research article "Modeling snow saltation: the effect of grain size and interparticle cohesion" published at the Journal of Geophysical Research: Atmospheres.The code is a f ...

2021

Study of Aerodynamic Grain Entrainment in Aeolian Transport

Aeolian transport controls landform formations on Earth and other planets and crucially affects the atmospheric system. With elaborate wind tunnel measurements, we find that the aerodynamic entrainment rate follows a yet unreported exponential increase in ...

2020

On the stabilizing effect of rotation in the 3d Euler equations

Klaus Martin Widmayer

While it is well known that constant rotation induces linear dispersive effects in various fluid models, we study here its effect on long time nonlinear dynamics in the inviscid setting. More precisely, we investigate stability in the 3d rotating Euler equ ...

2020

Understanding turbulent free-surface vortex flows using a Taylor-Couette flow analogy

Giovanni De Cesare

Free-surface vortices have long been studied to develop an understanding of similar rotating flow phenomena observed in nature and technology. However, a complete description of its turbulent three-dimensional flow field still remains elusive. In contrast, ...

Nature Publishing Group2018

Wind tunnel observations of weak and strong snow saltation dynamics

Michael Lehning, Enrico Paterna, Philip Crivelli

Theoretical considerations suggest that saltation dynamics is dominated by either aerodynamic entrainment or by a combination of ejection and rebound at a given time and location. Calling these two regimes weak and strong saltation, respectively, we have i ...

Amer Geophysical Union2017

Numerical simulation of 3D flow in right-angled confluences with bed elevation discordance in both converging channels

Ivan Stojnic

The paper studies a combined effect of bed steps (BS) in both converging channels on the 3D flow in a confluence with alpha = 90 degrees. Nine combinations of bed elevation discordance ratio values in the two channels are analysed. It is shown that: 1) a p ...

Elsevier Science Bv2016

Hydraulic performance of stepped spillway aerators and related downstream flow features

Stéphane Christian Olivier Terrier

To protect spillways against cavitation damage, adding a small air concentration to the flow close to the invert is efficient. Aerator performance on smooth chutes was therefore well studied in terms of air entrainment and downstream air concentration deve ...

EPFL2016

Second-order sensitivity of parallel shear flows and optimal spanwise-periodic flow modifications

François Gallaire, Edouard Boujo, Andrea Fani

The question of optimal spanwise-periodic modification for the stabilisation of spanwise-invariant flows is addressed. A second-order sensitivity analysis is conducted for the linear temporal stability of parallel flows U-0 subject to small-amplitude spanw ...

Cambridge University Press2015

Air Entrainment in Skimming Flow on Stepped Spillways: the Effect of an Abrupt Slope Change

Anton Schleiss, Michael Pfister, José Pedro Gamito de Saldanha Calado Matos, Mohammad Javad Ostad Mirza

Numerous stepped spillways were built during the last decades. In particular, a stepped spillway may be integrated economically into the downstream face of a RCC gravity dam, or on valley flanks besides embankment or rockfill dams, where slope changes may ...

2015

Flow separation at convex banks in open channels

Koen Blanckaert

Laboratory experiments in an open channel bend provide insight into the physics of convex bank flow separation occurring in a variety of channel configurations, including confluences and bifurcations. The edge of the zone of flow separation is characterize ...

Cambridge University Press2015

Modelling Small-Scale Drifting Snow with a Lagrangian Stochastic Model Based on Large-Eddy Simulations

Michael Lehning, Marc Parlange, Marc Diebold, Jan Overney, Gian-Duri Lieberherr

Observations of drifting snow on small scales have shown that, in spite of nearly steady winds, the snow mass flux can strongly fluctuate in time and space. Most drifting snow models, however, are not able to describe drifting snow accurately over short ti ...

Springer Verlag2014

A Comparative Study of the Local Heat Transfer Distributions Around Various Surface Mounted Obstacles

Peter Ott, Alexandros Terzis, Robert Wyssmann, Dirk Ullmer

In many engineering applications, heat transfer enhancement techniques are of vital importance in order to ensure reliable thermal designs of convective heat transfer applications. This study examines experimentally the heat transfer characteristics on the ...

Science Press2014

Open-loop control of a separated boundary layer

François Gallaire, Edouard Boujo

Linear optimal gains

G_{opt}(\omega)

are computed for the separated boundary-layer flow past a two-dimensional bump in the subcritical regime. Very large values are found, making it possible for small-amplitude noise to be strongly amplified and to desta ...

Elsevier France-Editions Scientifiques Medicales Elsevier2014

Relations between roughness, temperature and dry sliding friction at the atomic scale

Jean-François Molinari, Guillaume Anciaux, Peter Spijker

We investigate the friction of deformable bodies, with nano-scale self-affine fractal rough surfaces, at the atomic scale using molecular dynamics. Different temperatures (0-400 K) are studied, while roughness and applied load are changed. During sliding, ...

Elsevier Sci Ltd2013

Open-loop control of a separated boundary layer

François Gallaire, Edouard Boujo

Linear optimal gains

G_opt(\omega)

are computed for the separated boundary-layer flow past a two-dimensional bump in the subcritical regime. Very large values are found, making it possible for small-amplitude noise to be strongly amplified and to destabi ...

Cépaduès Editions2013

Performance study of a UWB antenna in proximity to a human arm

Anja Skrivervik, Nuno Miguel Faria Pires, Mohsen Koohestani

This letter studies the frequency- and time-domain performance of a recently developed printed coplanar-fed ultrawideband (UWB) monopole antenna aiming at predicting its behavior close to a human arm. The input reflection coefficient (|S11|) and fidelity f ...

Institute of Electrical and Electronics Engineers2013

Water-surface oscillations in channels with axi-symetric cavities

Anton Schleiss, Tobias Meile

Transverse or longitudinal movements of a water body are observed for flows along cavities, river embayments, groyne fields or harbours. They are significant for certain flow conditions and geometrical properties. To study the effect of large-scale roughne ...

Taylor & Francis Ltd2011

Characterization of the Flow Generated in an Annular Test Facility

Peter Ott, Elia Colombo, Dominique Charbonnier, Cécile Deslot

Annular cascades are particularly useful to study the three dimensional phenomena encountered in turbomachines. The Non-Rotating Annular Test Facility of the Swiss Federal Institute of Technology in Lausanne (EPFL) consists in a radial-axial inlet nozzle a ...

2011