Séminaire EDPAN

Avril 2026

• Jeudi 02 avril 2026 - Maëlle Labeille

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Mars 2026

• Jeudi 12 mars 2026 - Sarah Perez

  Bayesian and AI-Driven Uncertainty Quantification for Multiscale Problems in Porous and Fractured Media

  Uncertainty is inherent to the mathematical modelling of porous and fractured media, where multiscale heterogeneities, incomplete data, and model misspecification strongly affect predictive reliability. In this talk, I will present recent advances in Monte Carlo strategies and Bayesian Physics-Informed Neural Networks (B-PINNs) for forward and inverse problems arising in subsurface applications. I will discuss how such methods enable us to (i) assimilate 4D micro-CT data to infer reactive morphological changes at the pore scale, (ii) quantify and correct modelling errors in fracture conductivity laws, and (iii) reliably propagate uncertainties across scales when coupled with data-driven machine learning. Particular attention will be given to automatic task weighting for robust multi-objective Bayesian inference, and to hybrid particle/grid numerical solvers designed for pore-scale reactive flows. These contributions illustrate how mathematical modelling and modern AI techniques can be combined to better address uncertainty in multiscale porous-media systems.

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Février 2026

• Jeudi 05 février 2026 - Fabien Lespagnol

  A New Computational Approach for Fluid-Structure Interaction of Slender Bodies Immersed In Three-Dimensional Flows

  The term "slender" refers to structures with a very high ratio between their longitudinal lenght and their transverse dimensions, typically, a cylinder with an height significantly larger than its radius. Because of this particular geometry, many models have been developed to provide a simplified description of the kinematics and dynamics of the structure. A standard approach in this context is to account for the distribution of forces and deformations only along the centerline. Consequently, the velocity fields and equilibrium equations of the structure are described in a one-dimensional (1D) setting. However, when a slender structure is immersed in a three-dimensional (3D) fluid, enforcing kinematic and dynamic coupling conditions on a 1D domain requires the introduction of a double trace operator (codimension 2) which demands regularity for the solution within the fluid domain, a condition which is generally not satisfied a priori. In this talk, I will introduce and analyse a new mathematically sound approach for modelling and solving 3D–1D fluid–structure interaction problems. The main idea is to combine a fictitious domain approach with the projection of the kinematic constraint onto a finite-dimensional space defined along the structure’s centerline. The discrete formulation is based on the finite element method and a semi-implicit treatment of the Dirichlet-Neumann coupling conditions, employing a partitioned procedure for the resolution of the fluid-structure interaction problem.

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Janvier 2026

• Jeudi 29 janvier 2026 - Eduard Marušić-Paloka

  A new light on the interface condition between the fluid flow and the porous medium

  We study 3 situations where the domain filled with viscous fluid is in contact with porous object.
  The first situation is the simplest. The exterior boundary of the fluid domain is porous.
  The second situation is slightly more complicated. The thin porous interface is submerged in the fluid domain.
  The third situation is the most complicated. The fluid domain is in contact with a thick porous medium that has its own dynamics.
  Using the homogenization techniques and the boundary layers, in all 3 situations we derive the effective law that can be used for simulations on the macroscopic level. The effective law turns out to be of the same type. We call it the Darcy law on the boundary. It claims that the effective velocity on the interface is proportional to the difference between the stresses on different sides of the interface.

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• Jeudi 22 janvier 2026 - Jessie Levillain

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• Jeudi 15 janvier 2026 - Eloïse Comte

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• Jeudi 08 janvier 2026 - Journée d'équipe

  Journée d'équipe

  - 9h30 Accueil café
  Matinée en salle 218
  - 10h : réunion d'équipe
  - 10h10 : Ana Maria Orita: Some remarks on high-order finite-differences schemes. Consequences on the observability of the wave equation
  - 11h : Khalid Latrach: Sur l'existence des solutions d'une équation de transport stationnaire mono-dimensionnelle avec des neutrons retardés
  Déjeuner en salle 114
  Après-midi en salle 102
  - 13h : Mickael Dos Santos: Destruction de la supraconductivité. Effets ou absence d'effet d'impuretés diluées dans un supraconducteur
  - 13h50 : Thomas Giletti: Sur l'estimation à l'ordre logarithmique des lignes de niveau d'une équation de réaction-diffusion

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Décembre 2025

• Jeudi 18 décembre 2025 - Louis Garénaux

  Dynamique en temps long pour des équations de Klein-Gordon

  L'équation de Klein-Gordon est une équation des ondes avec un terme d'amortissement dû à la masse. Dans cette présentation, je ferai un état des lieux de la littérature traitant de la dynamique de cette équation lorsque le domaine spatial est non-borné et de dimension une. Je présenterai également des résultats nouveaux concernant l'existence globale et le comportement en temps long de solutions dont la condition initiale est constante ou périodique en espace.
  En particulier, je parlerai d'une approximation visqueuse de ce modèle, et je décrirai comment obtenir un résultat de stabilité orbital local et uniforme à partir d'une décomposition polaire.
  Les travaux présentés sont en collaboration avec Björn de Rijk et Emile Bukieda.

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• Jeudi 11 décembre 2025 - Emile Deléage

  A depth-averaged model for granular avalanches

  In this talk, I will present a new model of granular avalanches obtained in collaboration with Gaël Richard. The model is derived from a frictional rheology and is written as a hyperbolic system of conservation laws. As for the classical shallow water equations, the model computes the height and the depth-averaged velocity of the flow. A novelty of this work is the presence of a third variable, called enstrophy, which enables to model velocity variations within the flow. As an application, the model is used to study the roll waves instability and the shape of dry granular fronts.

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• Jeudi 04 décembre 2025 - Lucas Ertzbischoff

  Stability and instability for active Brownian particle models

  I will present a recent analysis of active Brownian particle systems, motivated by phase separation phenomena arising in such toy models for active matter. In a collaboration with M. Coti Zelati and D. Gérard-Varet, we rigorously justify (in)stability thresholds at the linearized level, with and without rotational diffusion.

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Novembre 2025

• Jeudi 20 novembre 2025 - Pas de séminaire...

  JEARA à l'ENS Lyon

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• Jeudi 06 novembre 2025 - Pas de séminaire...

  Visite HCERES

  

Octobre 2025

• Jeudi 23 octobre 2025 - Bérénice Grec

  A conservative two-phase flow model with a nonlinear degenerate diffusion

  This work is motivated by the need to model the dynamics of liquid-vapor flows involving phase transitions in heat exchangers. In the low Mach number asymptotic limit, we derive a system of 1D conservation laws with heat transfers causing phase change, with a degenerate and nonlinear thermal diffusion coefficient. This degeneracy induces discontinuities on the solution, both on the enthalpy and the velocity. We provide explicit steady and travelling wave solutions, and derive suitable numerical schemes able to capture the moving discontinuities.

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• Jeudi 02 octobre 2025 - Dongyuan Xiao

  Complete classification of traveling wave solutions to monotone dynamical systems

  To study the propagation phenomena of solutions to the reaction-diffusion equation the asymptotic behavior of traveling wave solutions plays a crucial role. When the nonlinear reaction term satisfies the monostable condition, it is known that there exists a minimal traveling wave speed, and that traveling wave solutions exist for any speed c larger than or equal to the minimal speed. It has been shown, through simple phase plane analysis, that these traveling waves can be classified into three cases based on their decay rates.
  
  Although such a classification is expected to be applicable to more complex order-preserving systems, such as nonlocal diffusion equations and the Lotka–Volterra model, a complete resolution has yet to be achieved due to the inapplicability of direct phase plane analysis. In this talk, I would like to introduce a method for classifying traveling waves in nonlocal diffusion equations and the Lotka–Volterra model. This research is based on joint work with Maolin Zhou (Nankai University) and Chang-hong Wu (National Yang Ming Chiao Tung University).

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Septembre 2025

• Jeudi 18 septembre 2025 - Weiwei Ding [lieu : Amphi Hennequin]

  Speed limits of time almost periodic traveling waves for rapidly/ slowly oscillating reaction-diffusion equations

  This talk is concerned with the wave propagation dynamics of time almost periodic reaction-diffusion equations. Assuming the existence of a time almost periodic traveling wave connecting two stable steady states, we focus on the asymptotic behavior of wave speeds in both rapidly and slowly oscillating environments. We prove that, in the rapidly oscillating case, the average speed of the time almost periodic wave converges to the constant wave speed of the homogenized equation. On the other hand, in the slowly oscillating case, the average speed converges to the arithmetic mean of the wave speeds for a family of equations with frozen coefficients. These explicit formulas for the limits of speeds also show the significant influences of temporal variations on wave propagation phenomena. Even in the periodic environment, it can alter the sign of bistable wave speeds.

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