Annonces et offres d'emploi

Important societal issues require to solve problems of increasing complexity. A key vector of progress relies on multi-scale and multi-physics approaches. The objective of the winter school is to review the different approaches, numerical and experimental techniques to tackle the complexity of today's engineering environmental and health-related problems. All the courses are illustrated through various up-to-date examples. Two days are devoted to practical laboratory work, combining experiments and numerical modeling. The last day of the school is dedicated to a particular theme. This year this day will be dedicated to "multiscale and multiphysical approaches in biomechanics".

Going back to Kolmogorov, there has been the paradigm in the more fundamental turbulence community of one universal state of homogeneous isotropic turbulence. In the last 15 years or so it has become more and more clear that this is not the case and that there can be several different states of turbulence, with transitions between these states. The transitions between the different states normally are of subcritical nature, just as the transition from laminar pipe or channel flow to turbulent pipe of channel flow. There, the origin of the subcritical nature is the nonnormality of the operator, combined with the nonlinearity of the Navier-Stokes equation. The nonnormality is intimately related to the local shear of the flow. All this also holds for turbulent flow, where one locally also has strong shear.

Multiphase flows are common in nature and engineering. Atmospheric flows often involve the dispersion of droplets or solid particulate matter (dust, sand, ice crystals in clouds); marine systems are populated by plankton, sediments or microplastics. Industrial applications of disperse flows include particle separators,filtration systems, atomisers and combustion devices, spray dryers, bubble columns; interfacial and free-surface flows are widespread in chemical and process industry.

Création de la Division Physique Non Linéaire (DPNL) de la Société Française de Physique (SFP)

Cet ouvrage présente les bases de la turbulence aux chercheurs en écologie marine, et les couplages de l’écologie marine avec la turbulence, aux chercheurs en turbulence provenant d’autres disciplines. Il s’adresse aux doctorants, jeunes chercheurs et chercheurs confirmés intéressés par ces deux sujets et leurs interactions.

The Leeds Institute for Fluid Dynamics is delighted to partner with the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge, the UK Fluids Network, and the Journal of Fluid Mechanics to deliver a regular webinar series on fluids-related topics.

Eligibility: Chinese citizens only due to the nature of the funding (CSC)Start date: September 2026 (for 3 years)Contact: julien.landel@univ-lyon1.fr

Eligibility: Chinese citizens only due to the nature of the funding (CSC)Start date: September 2026 (for 3 years)Contact: julien.landel@univ-lyon1.fr

We will investigate the interaction between weakly inhomogeneous turbu-lence and sedimenting particles which are larger than the smallest flow structures. The objectiveis to determine the influence of particle size and concentration on both the particle motion andthe fluid flow. The study, which will be carried out in collaboration with a partner team in Franceperforming laboratory experiments, can be expected to generate unprecedented data-sets al-lowing for new insight into long-standing problems.

Bubble columns are common in processes, i.e. biomethanation, hydrogen production, CO₂ sequestration... but their flow dynamics is not well understood. Indeed, in air–water bubble columns in the heterogeneous regime, collective dynamics plays a significant role [Mezui et al., JFM, 2022, 2023]. Meso-scale structures appear that induce buoyancy driven turbulent convection. Several questions remain: what controls these meso-scale structures? does an asymptotic heterogeneous state at exist high gas flow rates? what is the axial development of the flow?... When surfactants are added, a foam layer formq at the top of the column. A characterization of the bubble size inside the layer are necessary for understanding the dynamics, and for developing efficient separation processes. These flows will be investigated using Doppler optical probes [Lefebvre et al., CES, 2022]. Experiments and measuring technique are available. The post-doc will contribute to the collaboration with Shizuoka University.

The work proposed will investigate the interaction of a single fluid vortex and a liquid/gas interface in various configurations through theoretical/numerical modelling and stability analyses.

This project is a postdoctoral proposal in the stochastic physics of turbulence aiming to analyze stylized models of multifractal transport and to assess their relevance for turbulent transport.

Dans le cadre du projet « MAchine LEArning for Fluid system efficiency » (MALEAF), soutenu par l’Agence Nationale de la Recherche, l’Ecole Navale recrute un chercheur post-doctorant en mécanique des fluides expérimentale, analyse et assimilation de données d’écoulement pour 2 ans.Mots clés : PIV, POD, assimilation de données, modèle d’ordre réduit, hydrofoils

The wind turbine production in a floating wind farm depends essentially on its position, the wind and the state of the sea. The influence of the state of the sea, in particular, is poorly known, because it has not been an influential factor in the development of installed wind farms. First of all, the influence of the movement of the platform directly affects the production capacity of the wind turbine. But beyond that, it induces significant modifications to the wake, and in the context of commercial farms, where the turbines are not widely spaced, leads to interactions between turbines which are still unknown. As Numerical simulations are very expensive, from numerical simulation and historical data, the environmental conditions can be modeled by stochastic models which are faster to simulate. hus, by combining these stochastic models with the physical model, it is possible to evaluate the uncertainty relating to the key parameters (extractable energy, wake topology).

https://rejoindre.onera.fr/detail-poste?nPostingId=1327&nPostingTargetId=5036&id=P6VFK026203F3VBQB68LOF6Z3&LG=FR⟨uageSelect=FR

Le laboratoire J.A. Dieudonné souhaite recruter un.e Maître.sse de conférence pour renforcer son potentiel en recherche en mathématiques appliquées, avec un profil prioritairement orienté vers l’analyse numérique et le calcul scientifique.

Patrick Bot

V. Resseguier (INRAE), W. Antolin (INRAE), F. Dupuy (AgriOdor)

Machine Learning for the Control of Collective Dynamics in Particle-Laden Flows

Romain Monchaux (ENSTA Paris), Romain Volk and Mickaël Bourgoin (ENS Lyon)

Eletta Negretti

Pascale Bouruet-Aubertot, Yannis Cuypers, Julien Lenne

E. Negretti, O. Marchand

Bruno Issenmann et Christophe Pirat, en collaboration avec Guillaume Ricard (ENS Lyon) et Éric Falcon (Univ. Paris Cité)

Des microparticules déposées sur des surfaces et soumises à des flux d’air peuvent être remises en suspension. L’objectif du stage est de modéliser par les processus de Hawkes à partir de données d’expériences en laboratoire, la fraction de particules réémises en fonction de leurs propriétés, de leur mode de dépôt et des conditions de flux d’air. De manière générale les résultats doivent améliorer la prédiction et le contrôle des risques de contamination aéroportée, qu’elle soit d’origine inerte, chimique, biologique ou radioactive. Les microparticules étudiées dans ce stage sont pour le moment choisies pour leur adaptabilité aux conditions expérimentales mais à terme l'idée est d'élargir le spectre et d'aller vers des bioaérosols. Plus spécifiquement, cette recherche s’inscrira dans une démarche de réduction des risques liés à la propagation de spores ravageurs des cultures.

Eletta Negretti