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VERSION:2.0
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SUMMARY:MEchanics GAthering –MEGA- Seminar: Vortex breakdown in a hydrop
 ower draft tube swirling flow
DTSTART:20251127T130500
DTEND:20251127T140000
DTSTAMP:20260406T103912Z
UID:159412c8d3f2c16c2901fb9d881583dfb18dd21485463b5035195830
CATEGORIES:Conferences - Seminars
DESCRIPTION:Artur Gesla (HEAD\, EPFL)\nAbstact: In this talk we will explo
 re a vortex breakdown mechanism in the industrial flow inside a Francis hy
 dropower turbine. Vortex breakdown is a sudden change in a swirling flow s
 tructure when varying a flow control parameter. It can manifest as the for
 mation of an axisymmetric recirculation bubble or single- and double-helic
 al structures in the flow. Such a helical structure is present in the Fran
 cis turbine flow in the form of a vortex rope. Depending on the flow param
 eters\, the formation of the vortex rope can follow a simple  supercritic
 al Hopf scenario\, in which the base flow loses linear stability to monofr
 equency oscillatory dynamics\, or a much more complex one\, in which the b
 ase flow solution branch is characterised by multiple folds leading to sad
 dle-node bifurcations\, hysteresis loops\, and the system transiently visi
 ting the unstable solutions of the Navier–Stokes equations. We will show
  that the results of simplified laminar simulations can capture closely t
 he spatial structure and the frequency of the experimentally observed tur
 bulent vortex rope. Investigating the influence of turbulence on the rope 
 dynamics and on the proposed bifurcation scenario will be identified as a 
 main outlook of the present work.\n\nBio: Artur Gesla received the Aerosp
 ace Engineering Bachelor's degree from Warsaw University of Technology\, P
 oland\, in 2019 followed by the Computational Mechanics Master's degree fr
 om Technische Universität München\, Germany\, in 2021. His doctoral thes
 is "Numerical investigation of the dynamics of an axisymmetric rotor-stato
 r flow" prepared at Sorbonne Université and in LISN laboratory\, France\,
  has been defended in November 2024. From May 2025 he is a postdoctoral re
 searcher in HEAD group of prof.  Eunok Yim  at EPFL.\n 
LOCATION:ME B1 10 https://plan.epfl.ch/?room==ME%20B1%2010 https://epfl.zo
 om.us/j/67041786969?pwd=a1lXa3lsVGpvL1VpN2RDR2l4clg0QT09
STATUS:CONFIRMED
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