Reynolds stress modeling of turbulent open-channel flows

Numerical simulations of three-dimensional turbulent open-channel flows are presented. In the simulations, Reynolds-averaged Navier-Stokes equations are solved with the Reynolds stress model for turbulence closure. The Reynolds stress model consists of such sub-models as Speziale et al.'s model, Mellor and Herring's model, and Rotta's model for the pressure-strain correlation term, the turbulent diffusion term, and the dissipation term, respectively. These sub-models were selected based on the test results for various sub-models. The finite volume method is used for the numerical solution of the flow equations and transport equations of the Reynolds stress components. The overall solution strategy is the SIMPLER algorithm, and the power-law scheme is used to discretize the convection and diffusion terms in the governing equations. The Reynolds stress model is applied to rectangular open-channel flows, partlyvegetated open-channel flows, and compound open-channel flows. The simulated mean flow and turbulence structures including streamwise mean velocity, secondary currents, turbulence intensity, and Reynolds stress, are provided and compared with measure data in the literature. These comparisons reveal that the proposed Reynolds stress model successfully predicts the mean flow and turbulence statistics of turbulent open-channel flows.