THREE-DIMENSIONAL SIMULATION FOR EFFECTS OF BED DISCORDANCE ON FLOW DYNAMICS AT Y-SHAPED OPEN CHANNEL CONFLUENCES

Channel confluences are universally present in nature. They can be divided into two types:asymmetrical river confluences and symmetric river confluences. The latter is also called as the Y-shaped confluences. Most of previous work has paid more attention to the asymmetrical river confluences, but few studies have been conducted on the Y-shaped confluences. In this article, the effects of bed discordance on the flow patterns at"Y"shaped open-channel confluences were studied by using a 3-D numerical simulation. It is proved that the model can undertake quantitative assessment of the flow at confluences. The results indicate that there are a lot of differences between the Y-shaped confluence and asymmetrical confluence. The discordant bed height plays an important role at the Y-shaped junction.