[ANNULE] Large-scale dynamics of self-propelled particles moving through obstacles: how environment affects particle swarms

par Diane Peurichard (INRIA Paris)

mardi 28 mars 2023, 15:15 → 16:15 Europe/Paris

112 (Bâtiment Braconnier, La Doua)

We investigate the collective motion of self-propelled agents in an environment filled with obstacles that are tethered to fixed positions via springs. The active particles are able to modify the environment by moving the obstacles through repulsion forces. This creates feedback interactions between the particles and the obstacles from which a breadth of patterns emerges (trails, band, clusters, honey-comb structures,...). We derive a macroscopic partial differential equations model from the agent-based dynamics describing the interactions between the self-propelled particles and the obstacles, under large tether stiffness. We perform an in-depth investigation of pattern formation of the discrete and continuum models in 2D: we provide phase-diagrams and determine the key mechanisms for bifurcations to happen using linear stability analysis. As a result, we discover that the agent-agent repulsion, the agent-obstacle repulsion and the obstacle's spring stiffness are the key forces in the appearance of patterns, while alignment forces between the particles play a secondary role. We present an innovative methodology to compare discrete and continuum models that we apply here to perform an in-depth analysis of the agreement between the discrete and continuum models.