Fluid Mechanics Seminar: David Saintillan

  • Date: 11/06/2014
  • Time: 16:00

David Saintillan (University of California, San Diego)


David Saintillan is an Associate Professor in the Department of Mechanical and Aerospace Engineering. He received his undergraduate degree in Engineering from Ecole Polytechnique in France in 2001. He then obtained a Master's degree and a PhD in Mechanical Engineering from Stanford University in 2003 and 2006. He worked as a junior Research Scientist at the Courant Institute of Mathematical Sciences of New York University from 2006 until 2008, when he took a position as an Assistant Professor in Mechanical Science and Engineering at the University of Illinois Urbana-Champaign. He joined UC San Diego in December of 2013. He was the recipient of the Andreas Acrivos Dissertation Award in Fluid Dynamics in 2007, and of the Pi Tau Sigma Gold Medal in Mechanical Engineering in 2011.



University of British Columbia


Living fluids: modeling and simulation of active suspensions


Active suspensions, of which a bath of swimming microorganisms is a paradigmatic example, denote large collections of individual particles or macromolecules capable of converting chemical fuel into mechanical work and microstructural stresses in a viscous liquid. Such systems, which have excited much research in the last decade, exhibit complex dynamical behaviors such as large-scale correlated motions, pattern formation, enhanced diffusivities and mixing as a result of hydrodynamic interactions. In this work, we use a combination of theory and simulations to analyze these effects. First, a kinetic model is constructed and applied to elucidate the onset of spontaneous chaotic flows in semi-dilute suspensions. In isotropic and uniform systems, a linear stability analysis reveals the existence of a long-wave hydrodynamic instability for the active particle stress arising from self-propulsion, which drives large-scale fluctuations in suspensions of rear-actuated swimmers, or pushers, when the product of the linear system size with the suspension volume fraction exceeds a given threshold. This instability is confirmed by direct numerical simulations based on a slender-body model for interacting self-propelled particles, and is shown to capture all the salient features of experiments on bacterial suspensions. Extensions of these models to describe chemotactic interactions with an external oxygen field, the effective rheology of active suspensions, as well as the effects of confinement by rigid boundaries will also be discussed.

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Location: ESB 2012