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SUMMARY:Energy Spectrum for Buoyancy-Driven Turbulence - Abhishek Kumar\, 
 University of Coventry 
DTSTART:20180216T130000Z
DTEND:20180216T140000Z
UID:TALK101410@talks.cam.ac.uk
CONTACT:Charlotte Coles
DESCRIPTION:Buoyancy-driven flows are often encountered in geophysics\, as
 trophysics\, atmospheric and solar physics\, and engineering. In general\,
  these flows come in two categories: stably stratified flows and Rayleigh-
 Bénard convection (RBC). Turbulent aspects of these flows are an active f
 ield of research. An important unsolved problem in this field is how to qu
 antify the small-scale quantities\, e.g.\, spectra and fluxes of kinetic e
 nergy (KE) and potential energy (PE) of these flows. Using direct numerica
 l simulations performed at high resolution\, we demonstrate that the stabl
 y stratified turbulence at moderate stratification exhibits Bolgiano-Obukh
 ov scaling\, due to the conversion of kinetic energy to potential energy v
 ia buoyancy. We show that the KE flux decreases with the wavenumber (k) wh
 ich yield k^{-11/5} and k^{-7/5} scaling for KE and PE spectra respectivel
 y. For RBC\, we performed simulation at grid resolution 4096^3 on a cubica
 l box and have shown a delicate balance of dissipation and energy supply r
 ate by buoyancy. This balance leads to a constant KE flux and rules out th
 e Bolgiano-Obukhov scaling\, and we observe Kolmogorov’s spectrum [1-3].
 \nReferences:\n[1] Kumar\, Chatterjee\, and Verma\, Phys. Rev. E\, 90\, 02
 3016 (2014).\n[2] Kumar and Verma\, Phys. Rev. E\, 91\, 043014 (2015).\n[3
 ] Verma\, Kumar\, and Pandey\, New J. Phys.\, 19\, 025012 (2017).
LOCATION:JDB Seminar Room\, CUED
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