Numerical study of junction-angle effects on flow pattern in a river confluence located in a river bend

Rasool Ghobadian,Zahra Seyd Tabar,Parisa Koochak

doi:10.4314/wsa.v42i1.06

Rasool Ghobadian, Zahra Seyd Tabar + Show 1 more

Open Access

https://doi.org/10.4314/wsa.v42i1.06

Copy DOI

Journal: Water SA	Publication Date: Jan 29, 2016
Citations: 6	License type: cc-by

Affiliation: Razi University, Shahid Chamran University of Ahvaz

Abstract

The effect of main channel curvature on the flow pattern in river junctions is a complex and important issue. The 3-dimensional flow pattern in a river bend with a lateral or tributary channel is not only affected by the centrifugal force and pressure gradient but is also affected by the tributary channel’s momentum. Understanding this phenomenon requires extensive research: in this study the effect of 4 tributary junction angles, placed at a 45° angle from the beginning of the bend, is studied using SSIIM1 software. The effect of the junction angle on the vertical and transverse velocity profile, water level changes in the main channel, bed shear-stress distribution and secondary flow strength were evaluated. The results showed that by increasing the junction angle from 30° to 115° the streamwise velocity in the vicinity of the centre line and the inner wall of the bend increases. Increasing the junction angle also increases the separation zone dimensions, maximum bed shear stress, difference between the upstream and downstream water level in the junction and the secondary flow strength. Keywords: flow pattern, junction angle, 180 degree bend, SSIIM1 numerical model

Highlights

IntroductionThis complexity is because of their turbulence and intense 3-dimensional nature and because of their topography and depth variations
Water flow in rivers, especially meandering rivers, is very complex
In this research the SSIIM1 model was used to evaluate the effect of the tributary junction angle on the flow pattern in a 180° bend

Summary

Introduction

This complexity is because of their turbulence and intense 3-dimensional nature and because of their topography and depth variations. River junctions in natural meanders increase the flow pattern’s complexity. The effect of bending curvature on flow dynamics and sediment in channels has received a considerable amount of attention, only limited information about the effect of bending curvature on flow patterns in river junctions is available, and there have been very few studies considering river junctions in river bends. Roberts (2004) did an experimental and numerical investigation on river meanders.

Methods

Results

Conclusion