Abstract

In this study, we revisit the consequence of assuming equilibrium between the rates of production (P) and dissipation (∈) of the turbulent kinetic energy (k) in the highly anisotropic and inhomogeneous near-wall region. Analytical and dimensional arguments are made to determine the relevant scales inherent in the turbulent viscosity (νt) formulation of the standard k-∈ model, which is one of the most widely used turbulence closure schemes. This turbulent viscosity formulation is developed by assuming equilibrium and use of the turbulent kinetic energy (k) to infer the relevant velocity scale. We show that such turbulent viscosity formulations are not suitable for modelling near-wall turbulence. Furthermore, we use the turbulent viscosity (νt formulation suggested by Durbin (Theor. Comput. Fluid Dyn., vol. 3, 1991, pp. 1-13) to highlight the appropriate scales that correctly capture the characteristic scales and behavior of P/∈ in the near-wall region. We also show that the anisotropic Reynolds stress (u′¯v′¯) is correlated with the wall-normal, isotropic Reynolds stress (v′2¯) as -u′¯v′¯ = c′u (STL)(v′¯2), where S is the mean shear rate, TL =k/∈ is the turbulence (decay) time scale and c′u is a universal constant. 'A priori' tests are performed to assess the validity of the propositions using the direct numerical simulation (DNS) data of unstratified channel flow of Hoyas & Jiménez (Phys. Fluids, vol. 18, 2006, 011702). The comparisons with the data are excellent and confirm our findings.

Department(s)

Civil, Architectural and Environmental Engineering

Comments

National Science Foundation, Grant OCE-1151838

Keywords and Phrases

turbulence modelling; turbulent boundary layers; turbulent flows

International Standard Serial Number (ISSN)

1469-7645; 0022-1120

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2025 Cambridge University Press, All rights reserved.

Publication Date

10 Dec 2014

Download

Full Text Link

Share

 
COinS