Turbulence Modeling of Compound Open-Channel Flows Using Nonlinear ${\kappa}-{\varepsilon}$ Model

This paper presents a numerical model to investigate the mean and turbulence characteristics of compound open-channel flows. The nonlinear model, which is a non-isotropic turbulence model, is used for the turbulence closure. The experimental case in Tominaga and Nezu (1991) is simulated by the numerical model. The predicted isovel shows the secondary currents over the entire cross section and the twin vortices especially at the interface between the floodplain and the main channel. The magnitude of the secondary currents is seen to be similar to the observed one. The computed profiles of the bottom shear stress, eddy viscosity, Reynolds stress, and the turbulence kinetic energy appear to agree well with the measured data. Through the comparison with the profiles by the standard model, the effect of isotropic turbulence assumption on the numerical computation is also investigated.