Stretching in a model of a turbulent flow

PHYSICA D-NONLINEAR PHENOMENA

卷:238

Article

Baggaley, Andrew W.¹  Barenghi, Carlo F.¹  Shukurov, Anvar¹ 

[1] Univ Newcastle, Sch Math & Stat, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England

关键词: Turbulence simulation and modeling;    Chaos in fluid dynamics;    Isotropic turbulence;    Homogeneous turbulence;   

DOI  :  10.1016/j.physd.2008.10.013

来源: Elsevier

【 摘 要 】

Using a multi-scaled, chaotic flow known as the KS model of turbulence [J.C.H. Fung, J.C.R. Hunt, A. Malik, R.J. Perkins, Kinematic simulation of homogeneous turbulence by unsteady random fourier modes, J. Fluid Mech. 236 (1992) 281-318], we investigate the dependence of Lyapunov exponents on various characteristics of the flow. We show that the KS model yields a power law relation between the Reynolds number and the maximum Lyapunov exponent, which is similar to that for a turbulent flow with the same energy spectrum. Our results show that the Lyapunov exponents are sensitive to the advection of small eddies by large eddies, which can be explained by considering the Lagrangian correlation time of the smallest scales. We also relate the number of stagnation points within a flow to the maximum Lyapunov exponent, and suggest a linear dependence between the two characteristics. (C) 2008 Elsevier B.V. All rights reserved.

【 授权许可】

Free