2024-03-12 カリフォルニア大学サンディエゴ校(UCSD)
＜関連情報＞
- https://today.ucsd.edu/story/you-didnt-see-it-coming-the-spontaneous-nature-of-turbulence
- https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.132.104002
自然発生的な確率は、数回の渦の回転時間で熱ノイズさえも乱流の最大スケールまで増幅する Spontaneous Stochasticity Amplifies Even Thermal Noise to the Largest Scales of Turbulence in a Few Eddy Turnover Times
Dmytro Bandak, Alexei A. Mailybaev, Gregory L. Eyink, and Nigel Goldenfeld
Physical Review Letters Published: 6 March 2024
DOI:https://doi.org/10.1103/PhysRevLett.132.104002
ABSTRACT
How predictable are turbulent flows? Here, we use theoretical estimates and shell model simulations to argue that Eulerian spontaneous stochasticity, a manifestation of the nonuniqueness of the solutions to the Euler equation that is conjectured to occur in Navier-Stokes turbulence at high Reynolds numbers, leads to universal statistics at finite times, not just at infinite time as for standard chaos. These universal statistics are predictable, even though individual flow realizations are not. Any small-scale noise vanishing slowly enough with increasing Reynolds number can trigger spontaneous stochasticity, and here we show that thermal noise alone, in the absence of any larger disturbances, would suffice. If confirmed for Navier-Stokes turbulence, our findings would imply that intrinsic stochasticity of turbulent fluid motions at all scales can be triggered even by unavoidable molecular noise, with implications for modeling in engineering, climate, astrophysics, and cosmology.
