Abstract
Flow connection in channels is a phenomenon which frequently happens in rivers, water and drainage channels and urban sewage systems. The phenomenon appears to be more complex in rivers than in channels, especially at the y-junction bed joint that causes erosion and sedimentation at some areas resulting to morphological changes. Flow behavior at the channel junction area depends on variables such as channel geometry, discharge ratio, tributary width and y-junction connection angle of the channel, bed level changes at the bed joint, flow characteristic at the bed joint upstream and flow Froude number in different sections. In this research, fluent numerical model and junction angles of 30o, 45o & 60o are used to analyze and evaluate the effect of channel junction geometry on the flow pattern and the flow separation zone dimensions in different ratios of flow discharge (upstream channel discharge to total discharge of the flow). Results for two ratios of flow discharge are represented. Results are in agreement with earlier studies and it is shown that the change of the channel crossing angle affects the flow pattern in the main channel and also that the dimensions of the created separation zone in the main channel become larger when the crossing angle increases. This phenomenon can also be observed when the flow discharge ratio is lower. Analysis showed that the least dimension of the separation zone will be at the crossing angle of 45o .
Highlights
One of the flows which leaves important effects on river and channels bed i.e. erosion, scour and sedimentation is the so called transverse flow, which is formed as the result of the collision of two flows with similar or different characteristic
It was observed that the combination of main and tributary channel flow resulted in the formation of a secondary flow which is affected by the flow discharge ratio and the junction angle
In this article, flow profile and flow separation zone dimensions at three junction angles of 30°, 45° and 60° for flow ratio of Q*=0.083 and Q*=0.917 have been investigated by using a Fluent numerical model
Summary
One of the flows which leaves important effects on river and channels bed i.e. erosion, scour and sedimentation is the so called transverse flow, which is formed as the result of the collision of two flows with similar or different characteristic. [2] represented an equation to obtain flow depth ratio by solving of energy and momentum equations They analyzed transverse channels with the angles of 30o, 45o & 60o. Ramamurthy et al [4] studied flow characteristics at the confluence of a rectangular open channel of 90o including equal width and they analyzed the flow pattern at the confluence of channels by using three dimensional turbulence models and evaluated their results by using lab data. Results indicated that there is a linear relation between five dimensionless parameters which include the inflow ratio, the outflow ratio, the inflow Froude number in one direction and the outflow depth ratio They represented an acceptable prognosis about flow distribution at a channel junction. Qohari [7] analyzed the flow pattern at the 90o junction by using Fluent and lab models and resulted that the Fluent numerical model had the capability to simulate the flow dynamic at channels junction and that the simulation of the secondary flow at the junction of 90o was satisfying and that there was a correlation between the results
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