Postdoctorale position (M/F) at SPEC/CEA, Paris-Saclay

Job Description

Missions

Geophysical flows are characterized by extreme events, either very localized like storms, high dissipation, … or global, such as the turbulent bifurcation of the Kuroshio current. They are often very rare and unpredictable. The goal of the prost-doc will be to explore how they form, and whether they have precursors, by using simplified theoretical and numerical models.

A key question is whether the triggering occurs via small-scale extreme events that propagate to large scale, and whether one can identify precursors to the bifurcations.

A detailed check of this hypothesis thus requires multi scale tools, such as fluid dynamics on log lattice, LES or statistical kinetic theory based on small scale vortices. All these problems must be explored in the rotating, stratified environment existing in geophysical flows. The goal will be to build scaling laws of the phenomena, identify the statistical relevant properties, understand the processus triggering the transition through advanced statistical methods (kinetic theory, large deviation). Ideally, this will lead to the development of new subgrid models suitable for describing and forecasting turbulent bifurcations in natural and laboratory flows.


This project is included in a more ambitious project dedicated to the development of a strategy for identifying the precursor signals of rare events and/or bifurcations in turbulent flows.

Activity

The role of the post doc will be to develop the necessary techniques using the available tools. A comparison with direct simulations coming from collaborators of the project in Grenoble can also be developed.

Your Profil

Skills

This activity is inherently multidisciplinary with strong collaborations with other scientific fields, as applied mathematics or statistical physics. Fluid mechanics is ubiquitous in geophysical and industrial applications. Better understanding of flows will help to address major challenges to deal with new energy and environmental constraints. Collaborations with experts in climate modeling, geosciences and in renewable energy development have been set-up to respond to these societal issues.

The candidate must hold a doctorate degree in fluid mechanics or related topics. He must have a formation in non-linear physics, statistical theory and multi-scale turbulence phenomenology and modelling. Prior experience with the log-lattice framework is a plus..

Ky word: Theoretical and numerical Fluid Dynamics, Physics and modeling of Turbulence. Turbulent bifurcations. Subgrid modelling


Language skills:
Writing skills in English, ability to formulate/work on a scientific project

Ability to work in a large team

Applications must include a detailed CV

Your Work Environment

Joint Research Unit (UMR 3680) of the Centre National de la Recherche Scientifique (CNRS), and Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), SPEC carries out a wide range of research activities on condensed matter.

The recruited person will be assigned to the SPHYNX group. Its scientific topics cover a variety of fields: active matter, turbulence and applications to climate, glass and slow dynamics, magnetic and fracture properties of disordered solids, complex fluids, colloids, thermoelectricity & heat transfer, active matter and biological objects,… The common challenge, in all these systems, is to understand how a collective dynamics emerges at the macroscopic scale and can be described through a small number of parameters, without keeping track of all the microscopic degrees of freedom.

At Sphynx a dedicated team specializes in turbulent flows which dynamics remains an outstanding challenge of out-of equilibrium physics with important implications for industrial and natural settings. The research carried out at SPHYNX aims to characterize the energy pathways of such turbulent flows from the large injection scale to the tiny erratic dissipative structures. Focusing on flows driven by thermal convection, we have obtained an unambiguous observation of the 'ultimate regime' of thermal convection, at play in geophysical and astrophysical flows. We have developed a theory for the associated turbulent transport based on the study of idealized models of increasing complexity. Such large-scale properties of turbulent flows are intimately connected to the way the flow dissipates energy at small scale: turbulence induces intense dissipative structures at very small scale that remain out of reach to most experimental studies. We have developed a log-lattice framework allowing the exploration of extreme parameters regimes characteristics of geophysical flows.

Constraints and risks

none

Compensation and benefits

Compensation

between 2 991,58 € and 4 756,76 €

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

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