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SUMMARY:Virtual MEchanics GAthering -MEGA- Seminar: Talk 1 - Macroscopic m
 odelling of micro-structured porous surfaces\; Talk 2 - Efficient flapping
  propulsion with stiffness-distributed structures
DTSTART:20201029T161500
DTEND:20201029T173000
DTSTAMP:20260510T221430Z
UID:c2ef5fc15c03f46f8b1c0986aabfafe7e14bebd319512784eac36bc2
CATEGORIES:Conferences - Seminars
DESCRIPTION:Giuseppe Zampogna (LFMI\, EPFL) & Pierre Leroy-Calatayud (fle
 XLab\, EPFL)\nTalk 1: Macroscopic modelling of micro-structured porous sur
 faces\, by Giuseppe Zampogna (LFMI\, EPFL)\n\nAbstract: The dynamics of a
  fluid flowing across a thin permeable interface (i.e. a membrane) is an i
 ntrinsically multiscale phenomenon\, owing to very different scales at pla
 y\, rendering its description complex\, from both a physical and computati
 onal point of view. A clear explanation of the mechanisms at the basis of 
 membrane processes is then needed. Thanks to a multi-scale homogenization 
 technique we develop a reduced-order\, intuitive\, robust and computationa
 lly cheap model to simulate the hydrodynamic interactions between a rigid 
 membrane and a surrounding incompressible fluid flow. The model is able to
  provide a description of the micro- and macroscopic fluid behavior and co
 nsists of a constraint to be satisfied by the fluid velocity components\, 
 imposed within the fluid domain\, over a virtual smooth surface passing th
 rough the center of each membrane pore. It shows that the membrane produce
 s a jump in fluid stresses whose intensity and direction\, evaluated solvi
 ng problems at the microscale\, depend on the external flow and on the por
 e geometry. To assert the validity of the macroscopic model developed\, it
 s solution is compared with the solution of the full-scale problem.\n\nBio
 : Giuseppe Zampogna is a EuroTech PostDoc Fellow in the Laboratory of Flui
 d Mechanics and Instabilities at EPFL\, under the scientific supervision o
 f Prof. F. Gallaire. Before coming in Lausanne\, he has been postdoc at th
 e Institut de Mécanique des Fluides de Toulouse and he obtained a PhD in 
 fluid dynamics at the University of Genova in March 2016. He is particular
 ly interested in multi scale phenomena like fluid flows interacting with p
 oroelastic media\, rough surfaces and micro structured porous surfaces.\n\
 nEfficient flapping propulsion with stiffness-distributed structures\, by
  Pierre Leroy-Calatayud (fleXLab\, EPFL)\n\nAbstract: Flying insects and 
 many aquatic animals rely on flapping for locomotion. A feature commonly o
 bserved is that wings or fins\, respectively\, usually appear to be stiffe
 r at the root and more compliant at the tip. Recent computational works on
  idealized propulsors have shown that such distribution of flexibility may
  lead to better performances compared to the homogeneous case\, both in th
 rust production and efficiency\, with peaks related to fluid-structure res
 onances. In this talk\, I will present our experimental results on tapered
  elastomeric flappers moving in silicon oil. Different sets of tapered fla
 ppers are carefully fabricated to fix some chosen parameters\, such as the
  total mass or\, more importantly\, the mean stiffness. The control over t
 he latter quantity has often been overlooked in recent experimental studie
 s on flexible propulsor. Our method fills this gap and enables us to inves
 tigate the role of the distribution of stiffness accurately. Our results q
 ualitatively concur with the above considered computational work\, showing
  band-broadening for power and thrust production at the resonant peak\, as
  well as an overall higher efficiency for samples with increasing tapering
 . These results simultaneously further our understanding of flapping propu
 lsion and might orient the design of small aquatic or air vehicles in the 
 future. Investigation on the wake structure\, and more generally\, on the 
 physical mechanisms leading to such an increase are still ongoing.\n\nBio:
  Pierre Leroy-Calatayud obtained his B.Sc. and M.Sc. in Physics from the S
 wiss Federal Institute of Technology in Zurich (ETH Zürich) in 2017 and 2
 020\, respectively. He initially joined the fleXLab at EPFL as an exchange
  student to perform his Master’s Thesis. Since July 2020\, he is working
  there as a research assistant (within the EPFL’s Master Valorization pr
 ogram). During his studies\, he got the chance to get some experience in v
 arious fields of experimental physics such as quantum magnetism at ETH\, p
 hysics of exotic atoms at CERN\, or acoustic metamaterials at Hokkaido Uni
 versity.
LOCATION:Zoom: epfl.zoom.us/s/98393329833 Room Passcode: 349948 http://epf
 l.zoom.us/s/98393329833
STATUS:CONFIRMED
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