Orateur
Description
This presentation focuses on the simulation of dense granular media composed of macroscopic particles suspended in a viscous fluid, such as mud. These systems exhibit extremely complex macroscopic behavior. At the heart of these behaviors lie the microscopic physical interactions between neighboring particles, in particular lubrication effects induced by the interstitial fluid, as well as solid contacts. These interactions are essential not only for understanding immersed granular flows, but also in the broader 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 nature of these effects as the distance between particles goes to zero, giving rise to time singularities. In this talk, we will present new contact-dynamics-like models that account for both lubrication and solid contact, with or without friction. We will show that these models can be used to develop stable and robust numerical schemes. At each time step, the incremental problem to be solved is a constrained optimization problem. The presentation will be illustrated with numerical results. We will conclude with a brief discussion of how this type of microscopic model can inspire the construction of one-dimensional macroscopic models, in which the non-overlapping constraint at the particle scale naturally translates into a maximum-density constraint at the continuous level.