A comparative study of turbulence models in a transient channel flow

S Gorji,M Seddighi,C Ariyaratne,A.E Vardy,T O’Donoghue,D Pokrajac,S He

doi:10.1016/j.compfluid.2013.10.037

Abstract

The performance of a number of low-Reynolds number turbulence models is evaluated against direct numerical simulations (DNS). All models are applied to an unsteady flow comprising a ramp-type excursion of flow rate inside a closed channel. The flow rate is increased linearly with time from an initial Reynolds number of 9308 (based on hydraulic diameter and bulk velocity) to a final Reynolds number of 29,650. The acceleration rate is varied to cover low, intermediate and high accelerations. It is shown that among the models investigated, the k–ε models of Launder and Sharma (1974) and Chang et al. (1995) [28] and the γ–Reθ transition model of Langtry and Menter (2009) [38] capture well the key flow features of these unsteady turbulent flows. For the cases of low and intermediate acceleration rates, these three models yield predictions of wall shear stress that agree well with the corresponding DNS data. For the case of high acceleration, the γ–Reθ model of Langtry and Menter (2009) [38] and the k–ε model of Launder and Sharma (1974) yield reasonable predictions of wall shear stress.

Highlights

Unsteady turbulent flows are of interest to turbulence researchers because of their wide range of occurrence across many engineering disciplines
The present paper reports on a systematic study of the performance of a wide range of low-Reynolds number turbulence models used to predict the detailed flow characteristics of ramp-up-type unsteady flows in a channel
K-ω k-ω v2-f v2-f uv/U2b νt/ν turbulence models are often tuned for relatively high Reynolds number flows, and applying such models to relatively low Reynolds number flows can result in poor performance

Summary

Introduction

Unsteady turbulent flows are of interest to turbulence researchers because of their wide range of occurrence across many engineering disciplines. A large amount of on-going research is leading to a better understanding of the complex turbulence mechanisms present in such flows. Studies of unsteady turbulent flows are mainly conducted through two main categories; periodic and non-periodic. Numerical and experimental techniques have been employed to investigate the turbulent flow features associated with periodic changes of flow rate with time. The research includes study of the flow behaviour for a range of frequency, amplitude and mean flow rates in the case of pulsating flow. Efforts on correlating the data on such flows have led to nondimensional parameters representing the extent to which shear waves generated attenuate in terms of wall units

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Conclusion