Departure from the statistical equilibrium of large scales in forced three-dimensional homogeneous isotropic turbulence

Ding, Mengjie1,2; Xie, Jin-Han1,2; Wang, Jianchun3

2024-04-12

10.1017/jfm.2024.247

JOURNAL OF FLUID MECHANICS   影响因子和分区

0022-1120

1469-7645

We study the statistically steady states of the forced dissipative three-dimensional homogeneous isotropic turbulence at scales larger than the forcing scale in real separation space. The probability density functions (p.d.f.s) of longitudinal velocity difference at large separations are close to, but deviate from, Gaussian, measured by their non-zero odd parts. The analytical expressions of the third-order longitudinal structure functions derived from the Karman-Howarth-Monin equation prove that the odd-part p.d.f.s of velocity differences at large separations are small but non-zero. Specifically, when the forcing effect in the displacement space decays exponentially as the displacement tends to infinity, the odd-order longitudinal structure functions have a power-law decay with an exponent of -2, implying a significant coupling between large and small scales. Under the assumption that forcing controls the large-scale dynamics, we propose a conjugate regime to Kolmogorov's inertial range, independent of the forcing scale, to capture the odd parts of p.d.f.s. Thus, dynamics of large scales departs from the absolute equilibrium, and we can partially recover small-scale information without explicitly resolving small-scale dynamics. The departure from the statistical equilibrium is quantified and found to be viscosity-independent. Even though this departure is small, it is significant and should be considered when studying the large scales of the forced three-dimensional homogeneous isotropic turbulence.

homogeneous turbulence isotropic turbulence

SCI ; EI

英语

其他

National Natural Science Foundation of China["92052102","12272006","42361144844","12172161"] ; Laoshan Laboratory["LSKJ202202000","LSKJ202300100"]

Mechanics ; Physics

Mechanics ; Physics, Fluids & Plasmas

WOS:001200609100001

CAMBRIDGE UNIV PRESS

ENGINEERING

Web of Science

1.Peking Univ, Coll Engn, Dept Mech & Engn Sci, Beijing 100871, Peoples R China
2.Peking Univ, State Key Lab Turbulence & Complex Syst, Beijing 100871, Peoples R China
3.Southern Univ Sci & Technol, Dept Mech & Aerosp Engn, Shenzhen 518055, Peoples R China

Ding, Mengjie,Xie, Jin-Han,Wang, Jianchun. Departure from the statistical equilibrium of large scales in forced three-dimensional homogeneous isotropic turbulence[J]. JOURNAL OF FLUID MECHANICS,2024,984.

Ding, Mengjie,Xie, Jin-Han,&Wang, Jianchun.(2024).Departure from the statistical equilibrium of large scales in forced three-dimensional homogeneous isotropic turbulence.JOURNAL OF FLUID MECHANICS,984.

Ding, Mengjie,et al."Departure from the statistical equilibrium of large scales in forced three-dimensional homogeneous isotropic turbulence".JOURNAL OF FLUID MECHANICS 984(2024).