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 

Pages (fromto)  961973 
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