Hybrid Two-Level and Kinetic-Eddy Simulation Model for Numerical Investigation of Wall-Bounded Turbulent Flows

In this study, a hybrid modeling strategy developed by additive blending of the two- level simulation (TLS) model and the kinetic eddy simulation (KES) model and referred to as the hybrid TLS-KES model, is assessed for simulation of wall-bounded turbulent flows. The hybridization is performed in a manner so that the TLS model is used in the near-wall region and the KES model is used in the region away from the wall. The TLS model is a multi-scale approach, where a field variable is decomposed into its large-scale (LS) and small-scale (SS) components, and both LS and SS fields are obtained explicitly by employing modeling assumptions for the small scales. As it does not employ the notion of spatial filtering and eddy viscosity, therefore, it does not suffer from some of the limitations of the conventional eddy-viscosity-based large-eddy simulation (LES) models. On the other hand, KES is a two-equation based model, where transport equations for the local subgrid kinetic energy and length scale are solved, thus allowing the method to approach very large-eddy simulation (VLES), LES, and direct numerical simulation (DNS) in the limit of resolution of turbulence length scales corresponding to only large scales, grid size, and fully resolved, respectively. The generalized hybrid formulation and KES models are evaluated for their capabilities by simulating fully developed turbulent channel flow at three different frictional Reynolds numbers (Reτ), namely, 395, 590, and 950, and comparing with the reference DNS results. Additionally, the effects of near-wall LS grid resolution and the role of the blending function at Reτ = 395 are also examined.