Berlin 2018 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 53: Complex Fluids and Soft Matter (joint session DY/ CPP / BP)

DY 53.6: Talk

Wednesday, March 14, 2018, 16:45–17:00, BH-N 334

Confined Suspensions as Fluidic Hourglasses — Alvaro Marin¹, Henri Lhuissier², Massimiliano Rossi³, and •Christian J. Kaehler³ — ¹Physics of Fluids, University of Twente, The Netherlands — ²IUSTI, Marseilles, France — ³Bundeswehr University Munich, Germany

Objects of different nature are being forced through constrictions all the time: sand in an hourglass, particles in a fluid through a porous medium, blood through a narrowed vessel or people leaving a room in panic. In all these cases it is important to make sure that the system keeps continuously flowing, sometimes even lives are at risk. The case of particles in a fluid affects porous mediums, filters and membranes, which become unusable when clogged. We use microfluidic devices with a bottleneck of squared cross-section through which we force dilute polystyrene particle solutions with diameters comparable to the bottleneck size and down to one tenth its size. In low friction conditions and at certain opening sizes, we show experimental evidence of perfectly flowing particle system with no detectable clogging events even at its maximum concentration, just as it occurs in dry granular systems. We describe analytically such a transition by modelling the arch formation as a purely stochastic process, which yields a good agreement with the experimental data.