### Abstract

According to the celebrated Bolgiano–Obukhov (Bolgiano, J. Geophys. Res., vol. 64 (12), 1959, pp. 2226–2229; Obukhov, Dokl. Akad. Nauk SSSR, vol. 125, 1959, p. 1246) phenomenology for moderately stably stratified turbulence, the energy spectrum in the inertial range shows a dual scaling: the kinetic energy follows(i) ∼k

^{−11/5 }for k >k_{B}, and (ii) ∼k^{−5/3 }for k >k_{B}, where kB is the Bolgiano wavenumber. The k^{−5/3 }scaling, akin to passive scalar turbulence, is a direct consequence of the assumption that buoyancy is insignificant for k > k_{B}. We revisit this assumption, and using the constancy of kinetic and potential energy fluxes and simple theoretical analysis, we find that the k^{−5/3 }spectrum is absent. This is because the velocity field at small scales is too weak to establish a constant kinetic energy flux as in passive scalar turbulence. A quantitative condition for the existence of the second regime is also derived in the paper.Original language | English |
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Pages (from-to) | 961-973 |

Number of pages | 13 |

Journal | Journal of Fluid Mechanics |

Volume | 875 |

Early online date | 26 Jul 2019 |

DOIs | |

Publication status | Published - 25 Sep 2019 |

### Keywords

- stratified turbulence

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## Profiles

## Guha, Anirban

- Civil Engineering - Lecturer in Fluid Mechanics (Teaching and Research)

Person: Academic

## Cite this

Alam, S., Guha, A., & Verma, M. K. (2019). Revisiting Bolgiano–Obukhov scaling for moderately stably stratified turbulence.

*Journal of Fluid Mechanics*,*875*, 961-973. https://doi.org/10.1017/jfm.2019.529