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SUMMARY:Large-scale flow structures in turbulent Rayleigh-Bénard convecti
 on: Dynamical origin\, formation\, and role in material transport - Philip
 p Patrick Vieweg (University of Cambridge)
DTSTART:20240430T103000Z
DTEND:20240430T113000Z
UID:TALK216418@talks.cam.ac.uk
DESCRIPTION:The interplay of gravity with mass density inhomogeneities int
 roduces natural (thermal) convection and represents the essential mechanis
 m by which heat is transported in natural flows. Simultaneously\, natural 
 flows are often far more extended in the horizontal direction than in the 
 vertical one. Motivated by these two observations and the various geo- and
  astrophysical applications (e.g. the solar convection zone)\, 3-dimension
 al Rayleigh-B&eacute\;nard convection as the paradigm of thermal convectio
 n has been studied.\nThis talk will cover some recent results from studyin
 g the impact of thermal (and mechanical) boundary conditions on large-scal
 e flow structures in Rayleigh-B&eacute\;nard convection by means of direct
  numerical simulations. It will be shown that thermal boundary conditions 
 are crucial to the formation of long-living large-scale (turbulent) flow s
 tructures. In particular\, a slow transient aggregation process &mdash\; t
 hat only stops once the horizontal extent of the domain is reached &mdash\
 ; can be found once the fluid layer is subjected to Neumann-type constant 
 heat flux boundary conditions. As a result\, the temperature field in the 
 domain is separated into one extended hot and another extended cold region
 . We trace this mechanism of self-organisation of flow structures back to 
 secondary instabilities as well as an inverse cascade in spectral space. T
 he talk will finish with a brief overview of our work on the identificatio
 n of those large-scale flow structures by the use of unsupervised machine 
 learning based on Lagrangian particle data.\n&nbsp\;\nSelected references\
 n[1] P P Vieweg\, J D Scheel and J Schumacher\, &ldquo\;Supergranule aggre
 gation for constant heat flux-driven turbulent convection&rdquo\;\, Phys. 
 Rev. Research 3\, 013231 (2021). DOI: 10.1103/PhysRevResearch.3.013231\n[2
 ] P P Vieweg\, &ldquo\;Large-scale flow structures in turbulent Rayleigh-B
 &eacute\;nard convection: Dynamical origin\, formation\, and role in mater
 ial transport&rdquo\; (PhD thesis\, TU Ilmenau\, Germany\, 2023). DOI: 10.
 22032/dbt.58334
LOCATION:Seminar Room 1\, Newton Institute
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