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SUMMARY:Vortex formation in flapping dynamics and energy harvesting 
DTSTART:20140324T160000
DTEND:20140324T170000
DTSTAMP:20260407T002642Z
UID:2e9a87f094533f3d862226a84f0617f505a657430149ebfd363a44f9
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr Daegyoum Kim\, Brown University\, USA\nBio: Dr. Daegyoum Ki
 m is currently a postdoctoral scholar at Brown University. He obtained his
  Bachelor’s degree from Seoul National University in South Korea\, and r
 eceived his Master’s and Ph.D. degrees from Graduate Aerospace Laborator
 ies of California Institute of Technology. Dr. Kim was the recipient of Wi
 lliam F. Ballhaus Prize in recognition of his doctoral dissertation on thr
 ee-dimensional vortex formation and unsteady force generation of flapping 
 propulsion. As a postdoctoral scholar\, he conducted research on renewable
  energy harvesting at Caltech before moving to Brown University last year.
  His research interests include sustainable energy harvesting\, biofluid m
 echanics\, vortex dynamics\, fluid-structure interaction\, and bio-inspire
 d design.\nAbstract : The study on vortex formation and unsteady force gen
 eration offers insights into understanding the dynamics of flapping found 
 in nature and the performance of novel\, bio-inspired energy harvesting sy
 stems. First\, in order to find the effect of wing aspect ratio on thrust 
 generation\, three-dimensional vortex structures are investigated experime
 ntally using a model that mimics the clapping motion of butterfly wings. T
 he strength of the vortex structure generated by the model increases with 
 decreasing aspect ratio\, and the inner area enclosed by the vortex struct
 ure becomes larger as the aspect ratio is decreased. Hence\, in contrast t
 o the traditional aerodynamic theory\, the low aspect-ratio wings produce 
 larger thrust than the high aspect-ratio wings in some unsteady modes. In 
 addition\, self-excited flapping dynamics and instability are discussed fo
 r an inverted flag configuration with a free leading edge and a fixed trai
 ling edge\, which reveals quite distinct dynamical behaviors from those of
  a general flag. This inverted flag configuration was motivated by the tre
 e leaves fluttering in a breeze regardless of their orientation relative t
 o the wind direction. For the flapping inverted flag\, the time scale of o
 ptimal vortex formation correlates with the energy conversion of fluid kin
 etic energy to elastic strain energy. Lastly\, the energy harvesting perfo
 rmance of a periodically pitching and heaving hydrofoil similar to the fla
 pping fins of aquatic animals is examined. Flow visualization shows that t
 he shedding of the bound vortices critically limits the overall power gene
 ration of the hydrofoil while the development of leading-edge vortices con
 tributes to improved efficiency.
LOCATION:ME B3 31 http://plan.epfl.ch/?room=MEB331
STATUS:CONFIRMED
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