Large eddy simulations of turbulent circular wall jets

Turbulent circular wall jets have been extensively investigated both experimentally and numerically in the past decades. Most of the previous studies focus on the kinematic characteristics of the jet flows, while the mixing characteristics including the scalar transport have not been well examined. The current study performs a comprehensive investigation of the turbulent circular wall jet including both the flow and mixing characteristics using the large eddy simulations (LES) approach with proper near-wall modelling. The LES results are compared to the existing experimental measurements, as well as numerical results from two other Reynolds-averaged Navier-Stokes (RANS) models: the standard k-ε and standard k-ω models, with enhanced wall functions. The comparison focuses on the velocity and scalar distributions, rates of velocity and scalar decay, variations of characteristic length scales, and turbulence intensities in different directions. Overall, the study shows that LES coupling with proper near-wall modelling can simulate both the kinematic and mixing characteristics of the turbulent wall jet in a satisfactory manner, and the accuracy is superior to the RANS models with enhanced wall functions for this three-dimensional wall-bounded shear flow. The advantages can be attributed directly to the better simulations of the anisotropic jet spreading near the wall.