Coming up next
2025-01-16 - 13:30 @ New Gorleaus DM 1.15
SLAM SEMINAR: Camille Jorge (Martin's Guest)
Title: Active hydraulics
Abstract: We explore the behavior of active fluids confined in microchannel networks, demonstrating how they deviate from the predictable laws of classical hydraulics, which govern viscous, laminar flows. While traditional systems like blood vessels and porous media are described by robust, linear laws, active fluids exhibit bistable and non-deterministic dynamics. Through a combination of experiments, simulations and theory I will show how to build a general framework for predicting the geometry of active-hydraulic flows in arbitrary networks.
First, focusing on square-grid networks, experiments with colloidal rollers reveal that the degenerate flows of active fluids correspond to configurations of the six-vertex model. This quantitative correspondence enables us to predict and control the Lagrangian trajectories of active particles, which form completely packed loops, as described by the Baxter-Kelland-Wu framework. This experiment teaches us how to map active-hydraulic flows on vertex physics and and how to lay out the first free rules obeyed by all active hydraulic flows.
We then show that a crucial additional rule is required to account for geometry of active flows in network having an odd coordination number. We focus on trivalent networks and show show that active hydraulic flows act as dynamical spin-1 ices, resulting in degenerate streamline patterns. These patterns split into two geometric classes of self-similar loops, reflecting the fractionalization of topological defects at subchannel scales. From our observation we explain the interaction rules between the vertices that define active-hydraulic flows.
Our findings offer new perspectives on active fluid dynamics and provide a foundation for the design of microfluidic devices and the study of biological transport in complex environments.