# Laboratoire de Mécanique des Fluides et d’Acoustique - UMR 5509

LMFA - UMR 5509
Laboratoire de Mécanique des Fluides et d’Acoustique
Lyon
France

## Nos partenaires

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

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)