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SUMMARY:MEchanics GAthering -MEGA- Seminar: Kolmogorovian turbulence in tr
 ansitional pipe flows
DTSTART:20190228T161500
DTEND:20190228T171500
DTSTAMP:20260429T060545Z
UID:30d774f67c73d1d28f8be7ad11617f66a593457399c6b9679c0d0bda
CATEGORIES:Conferences - Seminars
DESCRIPTION:Gustavo Gioia\, Okinawa Institute of Science and Technology G
 raduate University\, Japan\nAbstract As everyone knows who has gradually
  opened a water faucet\, pipe flows are initially laminar but become turbu
 lent at high flow velocities. At intermediate velocities there is a transi
 tional regime in which plugs of laminar flow alternate along the pipe axis
  with ``flashes'' of fluctuating\, non-laminar flow. While it is known tha
 t flashes can fission\, decay\, and crowd out the intervening laminar plug
 s\, the nature of ``flash flow'' (the flow inside flashes) remains poorly 
 understood. In this talk we show experimentally that flash flow satisfies 
 the Blasius law of fluid friction\, which is diagnostic of turbulence\; th
 us\, flash flow is likely to be but turbulent flow. To verify this possibi
 lity\, we show that the statistics of flash flow are in keeping with Kolmo
 gorov's theory of the statistical structure of turbulence (so that\, for e
 xample\, at high wavenumbers\, the energy spectra of flash flow collapse o
 nto the energy spectra of turbulent flow\, consistent with small-scale uni
 versality)\, with the implication that transitional pipe flows are segrega
 ted mixtures of a laminar phase and a Kolmogorovian turbulent phase. Our f
 indings lend support to the widely-held notion that transitional pipe flow
 s signal a non-equilibrium phase transition to turbulence. This research w
 as carried out with Rory Cerbus\, Chien-Chia Liu\, and Pinaki Chakraborty\
 , OIST Graduate University.
LOCATION:MED 2 2423 https://plan.epfl.ch/?room=MED22423
STATUS:CONFIRMED
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