n° 197 Hommage à Alexandre Favre

Michel Coantic
IRPHE
Jeunesse et formation. L’ingénieur et le professeur. Premiers travaux : paroi mobile et compresseur. A. Favre et la turbulence : le L.M.A. puis l’I.M.S.T., son personnel et ses équipements. Les objectifs scientifiques : corrélations spatio-temporelles, bases de données, moyennes de Favre. L’industrie et la communauté scientifique. La famille et l’académie.
communication programmée pour mardi matin 9H30 salle J

n° 1300 Conférence d'ouverture : RANS Modelling of Some Strongly Swirling Aeronautical Flows

Brian Launder Tim Craft Hector Iacovides
MACE, the University of Manchester
Progress is reported on the modelling, via RANS closures, of two swirling turbulent flows important in aeronautics: the trailing wing-tip vortex and the flow in rotor-stator cavities. For the former the decay of the vortex is only well captured at second-moment level while, for the latter, an unsteady flow computation brings out large-scale organized structures, with the number of structures varying with cavity aspect ratio and Reynolds number, a result qualitatively in accord with experiment.
communication programmée pour mardi matin 9H50 salle J

n° 520 Stratified turbulence in coastal flows

Philippe Fraunié
LSEET UMR 6017
The turbulent diffusion in the coastal flow has been investigated from in situ and numerical experiments. A Lagrangian measurement approach for vertical profiles of temperature, salinity and momentum were used to parametrize the turbulent mixing as related to the local Richardslon number, using optimal control techniques. High order numerical modelling, including Large Eddy Simulations, allowed to explain secondary flows and filaments as observed from HF Doppler radar and satellite imagery.
communication programmée pour mardi matin 10H50 salle J

n° 1296 Dynamique d'un tourbillon fortement incliné dans un fluide stratifié

Patrice Meunier Nicolas Boulanger Stéphane Le Dizès
Institut de Recherche sur les Phénomènes Hors Equilibre
Nous nous intéressons expérimentalement à la dynamique d’un vortex incliné dans un fluide stratifié. Nous avons généré un tourbillon de pale dans une cuve stratifiée. Ce vortex possède un rayon critique pour lequel de fortes vitesses axiales sont générées, si la vitesse angulaire du vortex est suffisamment importante. La structure de cette couche critique est prédite théoriquement. Ces vitesses axiales déstabilisent le vortex très rapidement et créent un très fort mélange.
communication programmée pour mardi matin 11H10 salle J

n° 1380 From baroclinic instability to developed turbulence

Claude Cambon Guillaume Simon Fabien Godeferd Aziz Salhi
Laboratoire de Mécanique et d’Acoustique
The coupled effects of mean shear, density-stratification and system rotation are investigated in the context of strong turbulence, i.e. accounting for the baroclinic instability. Although there exists a large literature in the rotating shear case and the stratified shear case, with linear approaches, Direct or Large Eddy Simulations, very few studies consider the combined three ingredients in the context of distorted homogeneous turbulence.
communication programmée pour mardi matin 11H30 salle J

n° 1050 Internal gravity waves breaking above Great Meteor Seamount

Louis Gostiaux Hans van Haren
LEGI
We present a 19 days, high frequency record of temperature profiles above the eastern shelfbreak of the Great Meteor Seamount. Seamounts are known to be efficient regions for internal tides generation, but also participate in mixing and transport through nonlinear processes and wave breaking. We measured extreme overtuning events associated with the upgoing tidal flux pushing cold water up the slope. Strong shear also lead to small scale instabilities that are also resolved by our sensors.
communication programmée pour mardi matin 11H50 salle J

n° 1306 Conférence d'ouverture : Intermittent spatial structure of Turbulence

Julian Hunt
Centre for Polar Observation & Modelling
The study of turbulence structure, which was greatly stimulated by the leadership and experimental innovations of Alexandre Favre and his collaborators at Marseille, has had the ambitious aim of understanding simultaneously both its statistical properties and its spatial and temporal structure. New concepts of eddy dynamics and kinematics in turbulence have emerged from the very high Reynolds number simulations of Kaneda and detailed experimental and theoretical studies (JH,Westerweel, Eames).
communication programmée pour mardi après midi 13H40 salle J

n° 644 Wave turbulence in shallow water

Efim Pelinovsky Ira Didenkulova Ana Sergeeva
Institute of Applied Physics
Nonlinear random wave interaction in shallow water is studied. To compare with deep water, the dispersion in shallow water is weak and the correlation between spectral components is strong. It leads to soliton formation in random wave field. The wave random dynamics within KdV equation is analyzed numerically. The soliton propagation in random media is studied analytically. The transformation of the distribution function in the process of the wave runup on a beach is investigated.
communication programmée pour mardi après midi 14H20 salle J

n° 1351 Effects of airflow on hydrodynamic modulation of short surface waves by long waves

Paul Gang Chen
Laboratoire de Mécanique, Modélisation et Procédés Propres
A model is developed for the effects of airflow on hydrodynamic modulation of short surface gravity waves by a dominant long wave. The propagation of the short wave and distribution of its wavenumber and energy density with respect to phase of the long wave are specified by the kinematic conservation equation and the wind-forcing modified wave action equation, which are solved using linear ray theory and modelled by the Reynolds-averaged Navier-Stokes equations.
communication programmée pour mardi après midi 14H40 salle J

n° 1286 Law of spreading of the crest of a breaking wave

Patrice Le Gal Michael Le Bars Yves Pomeau Timothée Nicolas Timothée Jamin
IRPHE, CNRS - Aix-Marseille Université - ECM
Wave breaking can be seen as the manifestation of a singularity in the dynamics of the fluid surface. We show theoretically and experimentally that, for shallow water waves, their crests expand in the span-wise direction as the square root of time. We then explore another configuration where the focusing of the initially parabolic waves induces a widening of the breaking proportional to the power 3/2 of time as it follows the Huygens cusp shape.
communication programmée pour mardi après midi 15H00 salle J

n° 1388 Wave-induced effects on sea spray interactions over waves

Marc Francius Alexander M. J. van Eijk
LSEET
Despite considerable efforts in air-sea interaction studies, an accurate understanding and modeling of the sea spray generation and interactions with the lower atmospheric marine surface layer is still far from being reached. As a matter of fact, the sea spray or the marine aerosols are potentially important to a large number of processes in the marine boundary layer.
communication programmée pour mardi après midi 15H40 salle J

n° 1403 Towards a General Model for Finely Intricate Moving Random Multi-Phase Systems

Alain Mailliat Alexandre Petroff Fabien Anselmet Roland Borghi
Ecole Centrale Marseille
This presentation addresses multiphase system if their phase domains are distributed in finely intricate moving random patterns. From local discontinuous characteristics, continuous global quantities are defined through both space-time filters and probability averaging. Balance equations for global quantities are derived, new flux terms are indentified and discussed. Overview of aerosol transport through forest canopies is presented as the model application.
communication programmée pour mardi après midi 16H00 salle J

n° 1200 Turbulent flows interacting with varying density canopies

Laurence Pietri Alexandre Petroff Muriel Amielh Fabien Anselmet
IRPHE
In the case of dense and homogeneous canopies, it is well-known that canopy flows are similar to mixing layer flows (so-called mixing layer analogy). When the canopy becomes sparser, a transition between the mixing layer and the boundary layer perturbed by interactions between element wakes occurs. This transition has still to be fully understood and characterized. An experimental work has been developed in order to study this transition for various density canopies.
communication programmée pour mardi après midi 16H20 salle J

n° 1354 Turbulence and waves in numerically simulated slope flows

Evgeni Fedorovich Alan Shapiro
School of Meteorology
Direct numerical simulation (DNS) is applied to investigate properties of katabatic and anabatic flows along thermally perturbed (in terms of surface buoyancy flux) sloping surfaces in the absence of rotation. Numerical experiments are conducted for homogeneous surface forcings over infinite planar slopes. The simulated flows are the turbulent analogs of the Prandtl (1942) one-dimensional laminar slope flow. The simulated flows achieve quasi-steady periodic regimes at large times, with turbulent fluctuations being modified by persistent low-frequency oscillatory motions with frequency equal to the product of the ambient buoyancy frequency and the sine of the slope angle. These oscillatory wave-type motions result from interactions between turbulence and ambient stable stratification despite the temporal constancy of the surface buoyant forcing. The structure of the mean-flow fields and turbulence statistics in simulated slope flows is analyzed. An integral dynamic similarity constraint for steady slope/wall flows forced by surface buoyancy flux is proposed and quantitatively verified against the DNS data.
communication programmée pour mardi après midi 16H40 salle J