Offres de Thèses et Postdocs

The School of Science and Engineering at Reykjabik University (Iceland) is looking for a PhD student to work on the project “Lagrangian Dispersion in Mixed Convective Turbulence “.

The National Institute of Oceanography and Applied Geophysics - OGS and the University of Trieste are issuing a call for applications to 1 PhD positions in EARTH SCIENCE, FLUID-MECHANICS AND MATHEMATICS. INTERACTION AND METHODS (Cycle XXXVII - Academic year 2021-2022). The positions come with scholarship and will be carried out at the Division of Oceanography of the OGS. Applications close on June 7th, 2021 at 13.00 CET.

The Laboratory of Fluid Mechanics and Acoustics (CNRS, Ecole Centrale de Lyon) is seeking a highly qualified candidate for a post-doctoral research fellowship regarding the development of synthetic turbulent inflow conditions for high-fidelity Lattice Boltzmann simulations. Such methods have been developed in the context of NavierStokes approaches at the laboratory. The objective is here to adapt and extend those methods in the context of LBM, with a particular attention paid to the generation of noise.The successful candidate will be in charge of the development and implementation of turbulent inflow conditions in an in-house LB code (written in C++). Validations and evaluations will be carried-out on cases of increasing complexity: isolated boundary layer, compressor cascade and a fan configuration.

This project aims at providing numerical and theoretical support to two experimental groups of the SIMONS Collaboration Wave Turbulence (see below).

Multiple PhD positions are available at Eindhoven University of Technology in the field of turbulence research.

Le projet de R&D SLITHER (financement région AURA) s’inscrit dans une problématique persistante en maintenance aéronautique : le décapage automatisé complet des aéronefs. Aujourd’hui, le décapage des surfaces des aéronefs n’est toujours pas pleinement automatisable du fait de l’impossibilité de gérer la variabilité des couches de peinture, des formes des appareils et de la difficulté d’accès à certaines zones en environnement complexe, en particulier dans les ailes des avions.

The postdoc position is offered within Team CaliSto at Inria Sophia Antipolis Méditerranée. The team is working on the stochastic modeling applied to single-phase and multiphase flows through complex stochastic differential equations. This is done in collaborations with researchers that share interest in environmental applications (including meteorologists, hydro-physicists, physicists specialized in turbulence and two-phase flows modeling).

The aim of the present project is to develop an efficient solid wall treatment for LBM, including turbulent wall models. Several issues will be addressed, among which:• interpolation methods used within the Immersed-Boundary Method (IBM) or Cartesian meshes framework for solid boundary treatment [1-2]• use of a turbulent wall model in conjunction with immersed solid boundaries [3]• reconstruction of the density distribution functions of LBM at boundaries nodeswithin this framework (accuracy, mass conservation, ...)• reconstruction of macroscopic quantities on the solid surface for post-processing purposes (eg. calculation of aerodynamic forces applied on an airfoil)• extension to moving/deforming solid boundaries

This thesis will focus on internal tidal waves (at diurnal and semi-diurnal frequencies), and may further extend to other type of ocean internal wave (e.g. near-inertial waves).

We invite doctoral students to apply for a post-doctoral fellowship from the Institute of Mechanics and Engineering of Aix Marseille University (1 year, from October 2021 to October 2022).

Keywords: Large Eddy Simulation (LES), Combustion, Two-phase flows, Atomization, Anisotropic mesh, Mesh adaptation, Numerical schemes, Unstructured mesh.

The prediction of preferential orientation of anisotropic particles in turbulent flows is of importance because of the many implications it can bear for industria

When a heavy fluid is superimposed on a light fluid, the effect of gravity results in a so-called Rayleigh- Taylor instability which tends to bring the former below the latter. This instability has been extensively studied in inertia-dominated regimes and in the absence of a lateral confinement. Here we are interested in the case where viscous effects are dominant and fluids are confined inside a vertical or inclined cylindrical tube.

The objective of the present project is to develop a numerical tool for compressible flows, by use of unstructured meshes and the finite-element package FEniCS. This code will then be used to identify near-field fluctuations that optimally radiate sound, both in subsonic jets and in the flow around an airfoil. The study program is based on theoretical concepts from linear instability analysis and from aeroacoustics.

In atmospheric clouds, in industrial power plants, and in the pandemic we have been living, a crucial element is the interaction of small particles with the turbulent flow that carries them. Will two ice crystals collide and aggregate to form a snowflake? Will an ocean wave break and splash droplets in the atmosphere? How far will a drop of saliva travel in air? Particle-laden turbulent flows are ubiquitous and extremely challenging to predict: the chaotic motion of the fluid is intertwined with the particles’ ability to exchange momentum and energy at the microscopic scale, while also altering the flow globally.

Melting, dissolving, and erosion are processes that are frequently found in nature and technology. Contrary to common believe these three processes do not always smooth the surface, but rather form structures and sometimes even sharpen the surface. This leeds to the formation of e.g. ice scallops and pinnacles, for some examples of patterning and roughening. The continuously changing shape of e.g. a melting iceberg and its interaction with the external turbulence is very complicated as it involves three boundary layers: kinetic, thermal, and solutal (due to the salt concentration). The interaction between those boundary layers is highly complex and not understood. In particular, what is the effect of the surface roughness on the melting rate? The aim is to study the interaction of these boundary layers in a controlled lab environment such as to increase our understanding of these phenomena and their relevance on e.g. the melting rate of ice of icebergs and (tidal) glaciers, all important in view of global war

The objective of this postdoc position is to improve the CYCLONE library developed by RTECH, possibly by incorporating a different type of Immersed Boundary Method (IBM), such as the sharp interface method, which is presently under investigation at Pprime Institute.

A postdoctoral position is open to study experimentally the statistical properties of turbulence in a stratified medium in the Coriolis facility.

TWe are currently offering two PhD positions: Experimental measuremenst of multiphase flows and numerical simulations of multiphase flows.The official advertisement will be opened soon, but inquiries can be sent to Mrs. Müllner at christina.muellner@tuwien.ac.at

The von Karman Institute for Fluid Dynamics is offering many new and exciting job opportunities: 5 Postdoc Fellows, 2 PhD positions, Test Engineer, Facility Engineer, Financial Project Controller

Dans le contexte de changement climatique, il est parfois difficile de distinguer les influences anthropiques, de la variabilité naturelle, tant celle-ci est complexe et pourtant si importante qu’elle peut masquer les effets des activités humaines sur le climat. C’est notamment le cas pour la variabilité de la circulation atmosphérique, que les modèles numériques actuels ne reproduisent pas correctement. L’une des raisons est l’impossibilité pour ces modèles de simuler les processus physiques sur l’ensemble des échelles spatio-temporelles où elles se produisent et notamment comment différents processus à différentes échelles interagissent. Le but de la thèse est de comprendre le lien entre les grandes échelles spatio-temporelles des mouvements cohérents de l’atmosphère et les statistiques à l'échelle régionale des différents champs turbulents (vitesse, température, humidité, précipitations), et notamment les événements rares ou extrêmes.

L’objectif de cette thèse est de comprendre les mécanismes à l’origine du bruit de décrochage statique et dynamique à l’aide de simulations des grandes échelles ou de méthodes hybrides RANS-LES, et de proposer des méthodes de réduction en jouant sur la forme des profils (épaisseur et cambrure) et la forme du bord d’attaque.

Two years post-doctoral position on experimental/numerical fluid dynamics with applications to sub-surface oceans in icy moons. Collaboration with LPG Nantes and IPG Paris within the ANR COLOSSe project. Focus on mixing induced by topography in a stratified fluid.

La production d’énergie à ce jour a une importance majeure et dans ce contexte les sources renouvelables attirent de plus en plus l’attention. Les systèmes de production d’énergie renouvelable ont gagné en com- plexité afin d’optimiser la production et d’assurer sa stabilité.

The objective of this postdoc is to study the importance of the fluid miscibility on the RTI dynamics using highly resolved simulations with the pseudo-spectral code STRATOSPEC . A diffuse interface method relying on the Cahn-Hilliart equations will be coupled to the Navier-Stokes solver. To this aim, we propose to assess the efficiency of various semi- or fully implicit numerical methods. Computational resources for the simulations will be provided through the TGCC supercomputers. Different theories and models will be proposed to interpret the results.

A goal of this research project is to propose solutions to improve the performance of heat exchang-ers by using acombination of active control strategiestomaximise heat-transfer capacityalong the interface fluid/structureandminimise the pressure loss due to friction betweenthe fluid and the wall.