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SUMMARY:MechE Colloquium: Vortex ring collisions and fluctuation forces in
  turbulence
DTSTART:20250401T120000
DTEND:20250401T130000
DTSTAMP:20260612T073702Z
UID:085ff540139bb5c0779b07a1aca29f2b23f5d5a21a76e0cda0551099
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Rodolfo OSTILLA MONICO\, Mechanical Engineering and Ind
 ustrial Design\, University of Cádiz\nAbstract: In the first half of th
 e talk I will discuss numerical simulations of vortex ring collisions in a
 n attempt to understand the rapid formation of very fine scale turbulence 
 (or ’smoke’) from relatively smooth initial conditions. Different pert
 urbations to the ring vortex are added\, and their effect on the generatio
 n and amplification of turbulence is quantified. The underlying dynamics o
 f the vortex core is analyzed. The presence of Crow and elliptic instabili
 ties is used to explain the different dynamics: either turbulent reconnect
 ion or cloud formation. The asymptotic behaviour of the collision behaviou
 r is analyzed\, and a link to the turbulent energy cascade is revealed. In
  the second half of the talk I will discuss the discovery of a surprising 
 fluctuation-induced force between two plates immersed in homogeneous isotr
 opic turbulence using Direct Numerical Simulations. The force is a non-mon
 otonic function of plate separation. The mechanism of force generation rev
 eals an intriguing analogy with fluctuation-induced forces: energy in the 
 fluid is localised in regions of high vorticity\, or "worms"\, which have 
 a characteristic length scale. The magnitude of the force depends on the p
 acking of worms inside the plates\, with the maximal force attained when t
 he plate separation is comparable to the characteristic worm length. A key
  implication of our study is that the length scale-dependent partition of 
 energy in an active or non-equilibrium system determines force generation.
 \n\n\n\nBiography: Rodolfo Ostilla Mónico is an Emergia Researcher in Fl
 uid Mechanics at the University of Cádiz. After graduating in Aerospace E
 ngineering at the University of Seville in 2010\, he obtained a doctoral d
 egree at the Physics of Fluids group at the University of Twente in 2015. 
 He then spent some years in the United States\, first as a postdoctoral re
 searcher at Harvard University and later as an assistant professor at the 
 University of Houston\, before joining the University of Cadiz in 2022. Hi
 s research is mainly in the field of computational fluid mechanics\, with 
 particular interest in numerical simulations of convective flows\, vortex 
 ring collisions and more generally\, of turbulent systems.
LOCATION:MED 0 1418 https://plan.epfl.ch/?room==MED%200%201418 https://epf
 l.zoom.us/j/64267570786
STATUS:CONFIRMED
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