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SUMMARY:Biofilm streamers and fluid dynamics: from vortical flows at low R
 eynolds numbers to the unsteady dynamics of elastic filaments
DTSTART:20120323T130000
DTEND:20120323T140000
DTSTAMP:20260920T152854Z
UID:bd39397ebfe91a5cf30d5a4a26c7210e28e4a594ae4cb2ac9b1ce0e0
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Laura Guglielmini\, Stanford University\, Center for Turbu
 lence Research\, USA\nBacterial biofilms are ubiquitous in aquatic environ
 ments\, generally develops in flow and adherent to surface and interfaces 
 and have an enormous impact on medicine\, process industry and ecology.  
 Recent experiments observed the formation of thread-like biofilms\, called
  streamers\, in microchannels with corners and bends\, floating in the mid
 dle plane of the channel and connected to the side walls at the inner corn
 ers. Motivated by this observation\, we use numerical simulations and asym
 ptotic analysis to show that at low-Reynolds number\, in proximity of a co
 rner or a change in the curvature of the side wall\, the flow is three-dim
 ensional and pairs of counter-rotating secondary vortical structures are p
 resent. This fact suggests an underlying hydrodynamic mechanism for the fo
 rmation of streamers. Additionally\, we model the streamer as a slender el
 astic filament and we discuss its time evolution and final shape in a visc
 ous flow. Finally\, the mentioned experimental observations lead us to stu
 dy the response of an elastic fiber tethered to a plane wall and subjected
  to a stagnation point flow. We find that\, for a critical value of the ra
 tio between viscous and elastic forces\, the filament is susceptible to a 
 buckling instability at a supercritical bifurcation point. This last pheno
 menon is also relevant to a number of flow problems involving slender elas
 tic fibers.
LOCATION:BM 5202 https://plan.epfl.ch/?room==BM%205202
STATUS:CONFIRMED
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