Dynamics of vorticity moments in shell models of turbulence: A comparison with the Navier–Stokes equations
File(s)PRS-Arx-2024.pdf (1.8 MB)
Accepted version
Author(s)
Gibbon, John
Vincenzi, Dario
Type
Journal Article
Abstract
Shell models allow much greater scale separations than those presently achievable with direct numerical simulations of the Navier–Stokes equations. Consequently, they are an invaluable tool for testing new concepts and ideas in the theory of fully developed turbulence. They also successfully display energy cascades and intermittency in homogeneous and isotropic turbulent flows. Moreover, they are also of great interest to mathematical analysts because, while retaining some of the key features of the Euler and the Navier–Stokes equations, they are much more tractable. A comparison of the mathematical properties of shell models and of the three-dimensional Navier–Stokes equations is therefore essential in understanding the correspondence between the two systems. Here, we focus on the temporal evolution of the moments, or 𝐿2𝑚-norms, of the vorticity. Specifically, differential inequalities for the moments of the vorticity in shell models are derived. The contribution of the nonlinear term turns out to be much weaker than its equivalent for the three-dimensional Navier–Stokes equations. Consequently, pointwise-in-time estimates are shown to exist for the vorticity moments for shell models of any order. This result is also recovered via a high–low frequency slaving argument that highlights the scaling relations between vorticity moments of different orders. Finally, it is shown that the estimates for shell models formally correspond to those for the Navier–Stokes equations ‘on a point’.
Date Issued
2025-03-20
Date Acceptance
2024-11-21
Citation
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2025, 481 (2309)
ISSN
1364-5021
Publisher
The Royal Society
Journal / Book Title
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences
Volume
481
Issue
2309
Copyright Statement
© 2025 The Author(s). This is the author’s accepted manuscript made available under a CC-BY licence in accordance with Imperial’s Research Publications Open Access policy (www.imperial.ac.uk/oa-policy)
License URL
Publication Status
Published
Article Number
20240622
Date Publish Online
2025-03-20