Numerical Simulation of 3D Flow at Right-angled Confuence with and without Upstream Planform Curvature

Abstract

This paper aims at studying the effect of upstream planform curvature on the flow in the confluence hydrodynamics zone. To do this, a 3D numerical model is used for simulation of flow at right-angled confluences with three different planforms, all of them having the straight main-canal. These are the confluences with: 1) the straight tributary canal, 2) the right bend and 3) the left bend in the tributary. Special attention is paid to the flow defection and flow separation zones since the former affects transfer of momentum from the tributary to the main canal and the later affects transport capacity of the post-confluence canal. Results are discussed in terms of: 1) variations of the flow angles along the junction lines at different elevations above the bed, 2) variations of recirculation zone length and maximal width throughout the flow depth and 3) streamwise velocity distributions in the cross-sections downstream of the confluence.