Subgrid scale models for large eddy simulations of a confined rectangular jet

Large eddy simulations are performed and compared with experimental data obtained for a liquid-phase turbulent flow in a rectangular duct. Three streams initially separated by two splitter plates enter the duct and mix, with the central stream having a higher velocity than the outer streams. All simulations are for water at a Reynolds number of 50,000 (based on hydraulic diameter and flow rate). The numerical formulation is based on the pressure Poisson equation and employs a sixth-order compact finite-difference scheme for the spatial derivatives and a third-order compact Runge-Kutta scheme for the time derivative on a partially-staggered variable arrangement. Four subgrid scale models are tested: the standard Smagorinsky model, the dynamic eddy viscosity model, the mixed model and the structure function model. Wall functions are also tested. One-point and two-point statistical correlations such as mean velocity, velocity fluctuations, Reynolds stresses, dissipation rate and the turbulent kinetic energy are compared against those obtained from the experiments.