The effect of subgrid-scale modeling on LES of turbulent coaxial jets

Abstract

Large eddy simulation (LES) is an efficient technique to simulate turbulent flows of practical interest, based on the elimination of flow scales smaller than a characteristic length and direct resolution of the largest scales. There is a variety of subgrid-scale models available in the literature to describe the turbulence in small scales, with different levels of complexity and computational cost. Although many advances have been achieved since the development of the LES technique, there is still no consensus on a definitive subgrid model for generic use in engineering applications. The objective of this work is to analyze the effect of subgrid modeling in LES of turbulent coaxial jets. Simulations were carried out for a test problem using the Smagorinsky, Germano and velocity structure function models, and results were compared with experimental data from the literature. The best results for average properties were found with the Smagorinsky model with an optimal ad hoc coefficient, while the dynamic model of Germano was the one that best described the turbulent features. These results show that this type of comparative analysis is of fundamental importance to obtain reliable results when addressing new problems.