M/F researcher "Prediction of Bistable Flows and Extreme Events through High-Fidelity Simulations and Dynamic Mesh Adaptation"

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M/F researcher "Prediction of Bistable Flows and Extreme Events through High-Fidelity Simulations and Dynamic Mesh Adaptation" Sintesi in italiano (traduzione automatica): L'organizzazione cerca un ricercatore per comprendere i meccanismi fisici alla base dei cambiamenti di regime e degli eventi estremi nei flussi turbolenti. Il candidato lavorerà presso l'Unità di Ricerca Congiunta (UMR 5519) del CNRS, dell'Institut National Polytechnique de Grenoble e dell'Università Grenoble-Alpes. Le mansioni principali includono l'analisi di simulazioni numeriche ad alta fedeltà, l'identificazione di strutture coerenti e lo sviluppo di criteri di adattamento della mesh dinamica. È richiesta una laurea in ingegneria o fisica, con competenze in simulazioni numeriche e fluidodinamica. Il ricercatore dovrà anche pubblicare i risultati e partecipare a conferenze scientifiche. The candidate's mission will be to better understand the physical mechanisms leading to regime changes and extreme events in turbulent flows, and to use these insights to develop predictive numerical simulation strategies based on dynamic mesh refinement. A detailed analysis of high-fidelity numerical simulations will be carried out to identify coherent structures, multiscale interactions and precursors leading to bifurcations and extreme events. This analysis will seek to identify the dominant mechanisms controlling the appearance of such phenomena and to identify the regions of the flow which need to be finely resolved numerically. A second objective will be to develop new dynamic mesh refinement criteria, based on instantaneous quantities rather than converged statistics. This will ultimately result in a methodology allowing to automatically focus the computational effort on the critical spatio-temporal regions, enabling the predictive simulation of bistable flows and extreme events at a controlled numerical cost. • Perform and analyse high-fidelity numerical simulations (DNS/LES) of turbulent flows exhibiting bifurcations or bistable behaviour. • Identify coherent structures, multiscale interactions and precursor signatures associated with rare events and regime transitions. • Develop and implement new dynamic mesh adaptation criteria based on instantaneous flow quantities. • Assess and validate predictive simulation strategies. • Disseminate results through scientific publications and conference presentations. Joint Research Unit (UMR 5519) of the Centre National de la Recherche Scientifique (CNRS), the Institut National Polytechnique de Grenoble (Grenoble INP) and the University Grenoble-Alpes (UGA). LEGI carries out a wide range of research activities with a common ground: fluid mechanics and related transport phenomena. Scientific context : A wide number of turbulent flows present complex behaviour characterised by regime transitions, bifurcations, bistable dynamics or high-amplitude rare events. These phenomena often play a decisive role on the performance and the safety of the studied systems, as is the case in hydraulic fluid machinery, aerodynamic systems or geophysical phenomena. Such turbulent flows raise fundamental fluid mechanics questions: which physical mechanisms govern the transitions between different flow states? Are there any precursors allowing to predict a change of regime or the occurrence of an extreme event? Answering these questions can require high fidelity numerical simulations capable of finely describing the spatio-temporal dynamics of complex turbulent flows. Mesh quality is a key element enabling such simulations. The MOST team (Turbulence Modelling and Simulation) at LEGI laboratory develops state-of-the-art adaptive mesh refinement strategies in the YALES2 code for DNS and LES simulations. These approaches currently rely on statistical quantities, and have already enabled dramatic reduction of computational time when simulating complex flows, while at the same time being largely independent of user choices at mesh creation time. However, in the case of bistable or rare-event driven flows, these strategies may miss certain essential transitional flow structures, precisely because they are based on averaged quantities. The development of truly predictive numerical simulations of such phenomena thus requires a better understanding of the physical mechanisms driving the observed transitions, as well as the conception of dynamic mesh adaptation criteria capable of capturing such mechanisms in real time. The recruited person will be assigned to the MOST team. The research activities of the MOST (Modelling and Simulation of Turbulence) team focus on the numerical prediction of turbulent and multiphase flows with a broad range of objectives from fundamental understanding of flow properties to technologies optimization. The research team has the ambition to address all the needed scientific fields Annuncio in inglese. Fonte: Euraxess (Commissione europea).