Capillary rise of active matter

• Applicant: Professor Dr. Heiko Rieger
• Subject Area: Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 518780764

We study the capacity of active matter to rise in thin tubes against gravity and other related phenomena like wetting of vertical plates and spontaneous imbibition, where a wetting liquid is drawn into a porous medium. This capillary action or capillarity is well known in classical fluids and originates from attractive interactions between the liquid molecules and the container walls, and from the attraction of the liquid molecules among each other. Recently, we observed capillarity in a minimal model for scalar active matter with purely repulsive interactions, where an effective attraction emerges due to slowdown during collisions between active particles and between active particles and walls. Based on this observation we will answer three questions in this project: How robust is the capillary rise predicted by an active lattice gas model with respect to microscopic details of the considered active matter system? What is the mechanism behind the capillary rise in active matter system when attractive particle-wall interactions are absent and in how far are stationary particle currents responsible for it? Are there experimental realizations of the precited capillary rise of active matter, for instance by using active colloids and the experimental setup of the Lyon group, with whom we collaborate, and if yes, what are the underlying mechanisms.

• DFG Programme: Research Grants
• International Connection: France
• Co-Investigator: Dr. Adam Wysocki
• Cooperation Partner: Dr. Cecile Cottin-Bizonne