*Article* **Large-Eddy Simulation of an Asymmetric Plane Diffuser: Comparison of Different Subgrid Scale Models**

#### **Hui Tang 1,2,3, Yulong Lei 1,2,\*, Xingzhong Li 1,2 and Yao Fu 1,2**


Received: 14 September 2019; Accepted: 21 October 2019; Published: 29 October 2019

**Abstract:** Large-eddy simulation (LES) of separated turbulent flow through an asymmetric plane diffuser is investigated. The outcome of an actual LES depends on the quality of the subgrid-scale (SGS) model, as well as the accuracy of the numerical method used to solve the equations for the resolved scales. In this paper, we focus on the influence of SGS models for LES of the diffuser flow through using a high-order finite difference method to solve the equations for the resolved scales. Six resolutions are computed to investigate the influence of mesh resolution. Four existing SGS models, a new one-equation dynamic SGS model and a direct numerical simulation (DNS) are conducted in the diffuser flow. A series of computational analyses is performed to assess the performance of different SGS models on the coarse grids. By comparison with the experiment and DNS, the results produced by the new one-equation dynamic model give better agreemen<sup>t</sup> with experiment and DNS than the four other existing SGS models.

**Keywords:** large eddy simulation; subgrid scale model; diffuser; dynamic one equation model; Vreman model; separation
