CERAMATHS - DMATHS seminar: presentation by Aline Lefebvre-Lepot

The CÉRAMATHS mathematics department seminar will welcome Aline Lefebvre-Lepot (Paris-Saclay) at 2pm on Thursday, June 11, 2026, for the following talk:

Close interactions in immersed granular flows

This presentation focuses on the simulation of dense granular media composed of macroscopic particles suspended in a viscous fluid, such as sludge. These systems exhibit extremely complex macroscopic behaviors, including phenomena such as concentration instabilities and flow blockages.

At the heart of these behaviors lie microscopic physical interactions between neighboring particles, in particular lubrication effects induced by interstitial fluid, as well as solid contacts. These interactions are essential not only for understanding immersed granular flows, but also in the wider context of particle suspensions. Despite their importance, the influence of these microscopic mechanisms on the overall dynamics of the system remains poorly understood.

A major difficulty stems from the singular character of these effects when the distance between particles tends towards zero, introducing temporal singularities. In this talk, we will present new contact dynamics-type models, taking into account lubrication as well as solid contact, with or without friction. We will show that stable and robust numerical schemes can be built from these models. These schemes lead, at each time iteration, to the solution of a constrained optimization problem. We will illustrate the presentation with numerical results.