Laboratoire de Mécanique des Fluides et d'Acoustique - UMR 5509

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Laboratoire de Mécanique des Fluides et d’Acoustique

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Accueil > Équipes > Turbulence & Instabilités > Séminaires informels > Séminaires passés > Séminaires 2018

Mahendra K. Verma, I. I. T. Kanpur, Inde

Phenomenology of turbulent thermal convection

Jeudi 24 mai 2018, 13h, ECL, bât I11, salle de réunion RDC

Phenomenology of turbulent thermal convection

In this talk I will provide an overview of the recent developments on turbulent convection, namely—

(1) Using pseudospectral simulations of turbulent thermal convection at very high resolution ($4096^3$) and high Rayleigh number ($Ra = 1.1 ×10^{11}$) with unit Prandtl number, we conclude that convective turbulence exhibits behaviour similar to fluid turbulence, that is, Kolmogorov’s $k^{−5/3}$ spectrum with forward and local energy transfers, along with a nearly isotropic energy distribution. The energy transfer diagnostics provide a very useful diagnostics in this investigation.

(2) The viscous dissipation rate in turbulent convection is not $U^3/d$, but it is $(U^3/d)\,Ra^{-0.20}$. Also, the viscous dissipation in the bulk dominates those in the boundary layers. Using these results, we present a new formulae for the scaling of Reynolds and Nusselt numbers.

References :
(1) M. K. Verma, A. Kumar, and A. Pandey, Phenomenology of buoyancy-driven turbulence : recent results, New J. Phys. 19, 025012 (2017).
(2) S. Bhattacharya, A. Pandey, A. Kumar, and M. K. Verma, Complexity of viscous dissipation in turbulent thermal convection, arXiv:1801.01701 (2018).
(3) M. K. Verma, Physics of Buoyant Flows : From Instabilities to
Turbulence, World Scientific, Singapore (May 2018)


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