Numerical Calculation of Three-Dimensional Turbulent Flow in Compound Rectangular Open Channels

Abstract

The hydrodynamic response of the turbulent flow in a compound rectangular open channel to the flood plain depth, roughness, and symmetry and to the channel Reynolds number was demonstrated. The flow in the four basic asymmetric channels measured by Tominaga and Nezu (1991) was numerically simulated, as well as other channel configurations including symmetric channels. Turbulence was modeled by the energy dissipation model, combined with the algebraic stress model suggested by Naot and Rodi (1982). The three-dimensional flow with secondary currents in compound open channels was solved numerically using the parabolic pressure correction algorithm of Patankar and Spalding (1972). The examples suggest data bases for the estimation of friction factors, and for the mass exchange rate between the flood plain interior and its threshold. A possible explanation for the multi-cellular structure in wide open channels is also given.