On the unsteady behavior of turbulence models

TL;DR

This paper evaluates the performance of different turbulence models in unsteady flows, highlighting limitations of traditional models and proposing a new multiple-scale model with nonlocal interactions that better predicts turbulence behavior.

Contribution

The paper introduces a new multiple-scale turbulence model incorporating nonlocal interactions, improving predictions of unsteady turbulence dynamics.

Findings

Two-equation models are limited by spectral equilibrium assumptions.

A basic multiple-scale model improves some predictions but fails in dissipation rate timing.

The proposed nonlocal interaction model accurately captures frequency response features.

Abstract

Periodically forced turbulence is used as a test case to evaluate the predictions of two-equation and multiple-scale turbulence models in unsteady flows. The limitations of the two-equation model are shown to originate in the basic assumption of spectral equilibrium. A multiple-scale model based on a picture of stepwise energy cascade overcomes some of these limitations, but the absence of nonlocal interactions proves to lead to poor predictions of the time variation of the dissipation rate. A new multiple-scale model that includes nonlocal interactions is proposed and shown to reproduce the main features of the frequency response correctly.