Author(s): Cheng Zeng; Zhou Zhou; Ling Ling Wang; Jie Zhou
Linked Author(s): Cheng Zeng
Keywords: No Keywords
Abstract: Open-channel confluences are commonly formed due to the evolution of natural rivers, the drainage, sewerage and relevant controls used in hydraulic engineering. The flow structure in the junction region is complicated and three dimensional. Separation zone and shear face generate most turbulence in confluence junctions. The turbulence is anisotropic and leads to strong secondary circulations in the downstream main channel. The turbulence models based on the Boussinesq eddy-viscosity approximation, e. g., k-ε& k-ω, are incapable of fully describing the complex flow conditions present at the open-channel confluences. Reynolds stress model (RSM) is a non-isotropic turbulence model which determines the Reynolds stress by solving the Reynolds stress transport equations directly. In the present study, the 3D flow pattern at the confluences of two rectangular channels with right angle is simulated with Reynolds Stress Model. The governing equations are solved by the Finite Volume Method (FVM) and the flow is analyzed in terms of unsteady state. The volume of fluid (VOF) method is used to capture the interface of the water and air. The Weber’s experimental findings of right-angled combining flows are used to test the validity of the numerical model. Comparison of the numerical results and the experimental data indicates a close proximity in mean velocity profiles, water surface elevation profiles and resolved turbulence quantities. The simulated profiles with the k-εmodel and Smagorinsky model were compared and discussed. The distribution of the energy correction coefficient and momentum correction coefficient are calculated to describe the non-uniformity of flow velocity distribution along the downstream main channel.
Year: 2018