Effect of bed roughness on flow dynamics at Open Channel Confluences

Open-channel confluence is a common occurrence in many hydraulic structures. Flow dynamics in the junction field is too complex. Compared to experimental findings , three dimensional numerical simulation can be useful to obtain more comprehensive insight of dynamics of the flow and will be useful in the hydraulic engineering projects. This paper numerically investigates the three dimensional flow pattern at the 90 °, sharp edges, rectangular open-channel confluences, using Navier-Stokes equations and RNG K-ε turbulence model. The equations are solved by finite volume method and unsteady flow conditions. The flow is analyzed in two-phase conditions. In the beginning , the numerical model has been validated by comparing with experimental data of shumate (1998). Then , the effect of bed roughness on flow characteristics is investigated. The numerical results show that the width of the separation zone is reduced by bed roughness.

Keywords:

90(0) confluence angle , bed shear stress , numerical modeling , turbulent flow , bed roughness