Large Eddy Simulation of a Turbulent Polydisperse Spray Flow: a Comparative Study of Subgrid Scale Models and Droplet Injection Models

This study performs an investigation of the effects of the subgrid-scale and droplet injection models in the large eddy simulation (LES) of turbulent two-phase spray flows. Three LES subgrid-scale (SGS) models (Smagorinsky, wall-adapting local eddy viscosity, and dynamic Smagorinsky) and two droplet injection models (cone nozzle injection and conditional droplet injection) are validated to the experimental measurements. For both gaseous and liquid phases, all SGS models provide comparable results, indicating that the current two-phase flow field does not exhibit a pronounced sensitivity to the LES SGS model. As for different droplet injection models and spray dispersion angles, minimal differences are observed in the prediction of the gaseous mean and RMS velocity profiles. However, for the result of liquid phase, CDIM (conditional droplet injection model) predictions of the droplet mean diameter and velocity are in better agreement with experiments, and less sensitive to spray dispersion angle settings. While the CNIM (cone nozzle injection model) prediction of droplet diameter is less accurate when increasing the dispersion angle. The study suggests that turbulent two-phase spray flows are more influenced by the spray boundary conditions rather than the LES SGS models.