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arXiv · 2406.07235

Non-equilibrium fluctuations of the direct cascade in Surface Quasi Geostrophic turbulence

V. J. Valadão·T. Ceccotti·G. Boffetta·S. Musacchio
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Abstract

We study the temporal fluctuations of the flux of surface potential energy in Surface Quasi-Geostrophic (SQG) turbulence. By means of high-resolution, direct numerical simulations of the SQG model in the regime of forced and dissipated cascade of temperature variance, we show that the instantaneous imbalance in the energy budget originates a subleading correction to the spectrum of the turbulent cascade. Using a multiple-scale approach combined with a dimensional closure we derive a theoretical prediction for the power-law behavior of the corrections, which holds for a class of turbulent transport equations known as {\alpha}-turbulence. Further, we develop and apply a method to disentangle the equilibrium and non-equilibrium contribution in the instantaneous spectra, which can be generalized to other turbulent systems.

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V. J. Valadão, T. Ceccotti, G. Boffetta, S. Musacchio. 2024-06-11. Non-equilibrium fluctuations of the direct cascade in Surface Quasi Geostrophic turbulence. https://arxiv.org/abs/2406.07235

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