Steinman Hall #1M-22 (Levich Institute Conference Room)
École Polytechnique (PhD student – group of Blaise Delmotte and Camille Duprat)
“Sedimenting Flexible Fibers Against Obstacles in a Viscous Fluid”
Simultaneous Zoom: https://ccny.zoom.us/j/83700935571
The motion of flexible fibers often happens in complex media that are structured by obstacles. Examples range from the transport of biofilm streamers through porous media to the design of sorting devices for DNA molecules. For large number of such problems, their dynamics result from the complex interplay between internal elastic stresses, contact forces and hydrodynamic interactions with the walls and obstacles. In this talk, I will present numerical simulations, experiments and theoretical investigations exploring the dynamics of flexible fibers settling in a viscous fluid embedded with obstacles of arbitrary shapes. We find that the presence of obstacles may lead to two types of events: gliding and trapping. In particular, we observe nontrivial trapping conformations on sharp obstacles that result from a subtle balance between elasticity, gravity and friction. In the gliding case, a flexible fiber reorients and drifts sideways after sliding along the obstacle. The subsequent lateral displacement is large compared to the fiber length and strongly depends on its mechanical and geometrical properties. I will also show how these effects can be leverage to propose a new strategy to sort particles based on their size and/or elasticity.