Energy spectrum of buoyancy-driven turbulence

Abhishek Kumar, Anando G. Chatterjee, Mahendra K. Verma

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Using high-resolution direct numerical simulation and arguments based on the kinetic energy flux Πu, we demonstrate that, for stably stratified flows, the kinetic energy spectrum Eu(k)∼k-11/5, the potential energy spectrum Eθ(k)∼k-7/5, and Πu(k)∼k-4/5 are consistent with the Bolgiano-Obukhov scaling. This scaling arises due to the conversion of kinetic energy to the potential energy by buoyancy. For weaker buoyancy, this conversion is weak, hence Eu(k) follows Kolmogorov's spectrum with a constant energy flux. For Rayleigh-Bénard convection, we show that the energy supply rate by buoyancy is positive, which leads to an increasing Πu(k) with k, thus ruling out Bolgiano-Obukhov scaling for the convective turbulence. Our numerical results show that convective turbulence for unit Prandt number exhibits a constant Πu(k) and Eu(k)∼k-5/3 for a narrow band of wave numbers. © 2014 American Physical Society.
Original languageEnglish (US)
JournalPhysical Review E
Issue number2
StatePublished - Aug 25 2014
Externally publishedYes

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: Our numerical simulations were performed at the Centre for Development of Advanced Computing (CDAC) and the IBM Blue Gene P “Shaheen” at KAUST supercomputing laboratory, Saudi Arabia. This work was supported by a research grant (Grant No. SERB/F/3279) from the Science and Engineering Research Board, India. We thank Ambrish Pandey, Anindya Chatterjee, Pankaj Mishra, and Mani Chandra for valuable suggestions.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.


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