Hydrodynamic shocks in microroller suspensions

Blaise Delmotte, Michelle Driscoll, Paul Chaikin, Aleksandar Donev

Research output: Contribution to journalArticlepeer-review


We combine experiments, large-scale simulations, and continuum models to study the emergence of coherent structures in a suspension of magnetically driven microrollers sedimented near a floor. Collective hydrodynamic effects are predominant in this system, leading to strong density-velocity coupling. We characterize a uniform suspension and show that density waves propagate freely in all directions in a dispersive fashion. When sharp density gradients are introduced in the suspension, we observe the formation of a shock. Unlike Burgers' shocklike structures observed in other active and driven confined hydrodynamic systems, the shock front in our system has a well-defined finite width and moves rapidly compared to the mean suspension velocity. We introduce a continuum model demonstrating that the finite width of the front is due to far-field nonlocal hydrodynamic interactions and governed by a geometric parameter, the average particle height above the floor.

Original languageEnglish (US)
Article number092301
JournalPhysical Review Fluids
Issue number9
StatePublished - Sep 2017

ASJC Scopus subject areas

  • Computational Mechanics
  • Modeling and Simulation
  • Fluid Flow and Transfer Processes


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