BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Memento EPFL//
BEGIN:VEVENT
SUMMARY:Mechanics of thin elastic rods: engineering meets computer graphic
 s
DTSTART:20160210T133000
DTEND:20160210T143000
DTSTAMP:20261005T001411Z
UID:f7ac3b2074d0917281e3445f94ffed368b2b912013bf51567a50ebbd
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. M. Khalid Jawed\, Department of Mechanical Engineering\, M
 assachusetts Institute of Technology\, Cambridge MA\nBio: Khalid Jawed is 
 a PhD candidate in mechanics at the Department of Mechanical Engineering\,
  Massachusetts Institute of Technology. His research focuses on the mechan
 ics of slender rods\; e.g. fuel pipelines\, knots in ropes\, bacterial fla
 gella. He attained his Master’s degree from the same institution in 2014
 . He received his undergraduate degrees in Aerospace Engineering and Engin
 eering Physics from the University of Michigan in 2012. His research inter
 est lies in developing numerical tools and computerized systems to exploit
  the functionality of materials.\nThin rods are ubiquitous in both nature 
 (e.g. bacterial flagella\, human hair) and engineering (ropes\, cables)\, 
 from the micron to the kilometer scale\, and often undergo extreme deforma
 tion. The geometric nonlinearities that result from the deformation proces
 s pose enormous challenges to traditional analytical and numerical tools. 
 Moreover\, it is often unfeasible to perform experiments at the original l
 ength scale of these systems. We overcome these challenges by combining mo
 del experiments and cutting-edge computational tools ported from computer 
 graphics\, towards developing predictive physical understanding of these s
 ystems. The prominence of geometry in this class of systems enables the sc
 aling (up or down) of the problem to the desktop scale\, which allows for 
 systematic experimental exploration of parameter space. In parallel\, we c
 onduct numerical simulations using the Discrete Elastic Rods (DER) method\
 , which was originally developed for the animation industry for special ef
 fects of the visually dramatic dynamics of hair\, fur\, and other rod-like
  structures. For the first time\, we port DER into engineering as a predic
 tive computational tool and test ride it against our own model experiments
  by studying two a priori unrelated problems\, at disparate length scales.
  The excellent agreement found between experiments and simulations illustr
 ates the predictive power of our approach. Scaling (up or down) to the ori
 ginal application then offers unprecedented tools for rationalization and 
 engineering design.\n(i) Laying of submarine cables onto the seabed (kilom
 eter scale). We developed a model system to study the nonlinear coiling pa
 tterns that emerge when a thin elastic rod is deployed onto a moving subst
 rate (conveyor belt). Excellent quantitative agreement is found between ex
 periments and the DER simulations\, with no fitting parameters. We identif
 y the characteristic length scales\, systematically explore parameter spac
 e and map out phase diagrams. Particular emphasis is given to the sinusoid
 al patterns (the first mode of instability) for which we find a close-form
  analytical description.\n(ii) Locomotion of single-flagellar bacteria (mi
 cron scale). We consider a macroscopic analog model to study the rotation 
 of a helical elastic rod immersed in a viscous fluid\, at low Reynolds num
 bers. We tackle this fluid-structure interaction problem (elastic forces c
 ouple to hydrodynamics) by implementing Lighthill’s slender body theory 
 into DER to fully capture the geometrically nonlinear configurations of th
 e rod. Our numerics are again in excellent quantitative agreement with exp
 eriments\, with no fitting parameters. A novel mechanical instability is u
 ncovered\, whereby the flagellum buckles above a critical rotation frequen
 cy. We demonstrate that bacteria in nature swim close to this threshold fr
 equency\, and therefore can possibly exploit this instability for physiolo
 gical purposes\, e.g. to change its swimming direction.\nThis research was
  performed with Pedro Reis (MIT)\, Noor Khouri (MIT)\, Eitan Grinspun (Col
 umbia University)\, and Fang Da (Columbia University).
LOCATION:MEB10 http://plan.epfl.ch/?lang=fr&zoom=19&recenter_y=5864108.228
 94&recenter_x=731002.1372&layerNodes=fonds\,batiments\,labels\,information
 \,parkings_publics\,arrets_metro\,transports_publics&floor=1&q=meb10
STATUS:CONFIRMED
END:VEVENT
END:VCALENDAR