Fig. 1: Active hydraulics in trivalent networks.
a, Macroscopic picture of a trivalent microfluidic network. It encloses a two-dimensional active fluid made of flocking Quincke rollers. b, Experimental streamlines measured in this active hydraulic network. The streamlines form self-avoiding loops coloured by their handedness. c, Close-up view of the experimental device. We can distinguish steady vortices in a finite fraction of the channels. d, Our results do not depend on the specific geometry of the nodes that connect the microfluidic channels. A node including a star-shaped flow splitter (top). A node with no splitter (bottom). In the steady state, only two of the three channels support laminar flows. The third (horizontal) channel hosts a steady vortex. e, Distribution of the roller density normalized by the average density in the channels. The density is homogeneous in all the experiments, but features fewer fluctuations when the nodes include a star-shaped splitter. f, Distribution of local edge current Φe normalized by Φ0 = 400 s−1. The distribution is trimodal for both node geometries (the sign convention used to define Φe is sketched and explained in Fig. 2a). PDF, probability distribution function.
