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SUMMARY:Turbophoresis of heavy inertial particles in statistically homogen
 eous flow - Jeremie Bec (CNRS (Centre national de la recherche scientifiqu
 e)\, INRIA Sophia Antipolis)
DTSTART:20220309T160000Z
DTEND:20220309T170000Z
UID:TALK170699@talks.cam.ac.uk
DESCRIPTION:Dispersed particles suspended in turbulent flows are widely en
 countered in nature or industry&nbsp\;under the form of droplets\, dust\, 
 or sediments. When they are heavier than the fluid\, such&nbsp\;particles 
 possess inertia and are ejected by centrifugal forces&nbsp\;from the most 
 violent vortical&nbsp\;structures of the carrier phase. Once cumulated alo
 ng particle paths\, this small-scale mechanism&nbsp\;produces an effective
  large-scale drift where particles leave the excited turbulent zones and&n
 bsp\;converge to calmer regions&nbsp\;to form uneven spatial distributions
 . This fundamental phenomenon\,&nbsp\;called turbophoresis\, has been exte
 nsively used to explain why particles transported by non-homogeneous flows
  concentrate near the minima of the turbulent kinetic energy.It is here sh
 own that turbophoretic effects are just as crucial in statistically homoge
 neous and&nbsp\;isotropic flows. Instantaneous spatial fluctuations of the
  turbulent activity\, despite their uniform&nbsp\;average\, trigger local 
 fluxes that play a key role in the&nbsp\;emergence of inertial-range inhom
 ogeneities&nbsp\;in the particle distribution. Direct numerical simulation
 s are used to thoroughly probe and depict&nbsp\;the statistics of particle
  accelerations and in particular their scale-averaged properties condition
 ed&nbsp\;on the&nbsp\;local turbulent activity. They confirm the relevance
  of the local energy dissipation to&nbsp\;describe instantaneous spatial f
 luctuations of turbulence. This analysis yields an effective coarse-&nbsp\
 ;grained dynamics\, in which particles detachment from the fluid&nbsp\;and
  their ejection from excited&nbsp\;regions are accounted for by a space an
 d time-dependent non-Fickian diffusion.
LOCATION:Seminar Room 1\, Newton Institute
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