Confluences play a major role in the dynamics of networks of natural and man-made open channels, and field measurements on river confluences reveal that discordance in bed elevation is common.Studies of schematized co...Confluences play a major role in the dynamics of networks of natural and man-made open channels, and field measurements on river confluences reveal that discordance in bed elevation is common.Studies of schematized confluences with a step at the interface between the tributary and the main channel bed reveal that bed elevation discordance is an important additional control for the confluence hydrodynamics.This study aimed to improve understanding of the influence of bed elevation discordance on the flow patterns and head losses in a right-angled confluence of an open channel with rectangular cross-sections.A large eddy simulation (LES)-based numerical model was set up and validated with experiments by others.Four configurations with different bed discordance ratios were investigated.The results confirm that, with increasing bed elevation discordance, the tributary streamlines at the confluence interface deviate less from the geometrical confluence angle, the extent of the recirculation zone (RZ) gets smaller, the ratio of the water depth upstream to that downstream of the confluence decreases, and the water level depression reduces.The bed elevation discordance also leads to the development of a large-scale structure in the lee of the step.Despite the appearance of the large-scale structure, the reduced extent of the RZ and associated changes in flow deflection/contraction reduce total head losses experienced by the main channel with an increase of the bed discordance ratio.It turns out that bed elevation discordance converts the lateral momentum from the tributary to streamwise momentum in the main channel more efficiently.展开更多
The advantages of the eastern coastal economic zone and its role in the country’s economic construction as well as its relationship with the western zone are discussed.
In April of 1988,the establishment of Hainan Province was officially approved at the first session of the 7th National People’s Congress and Hainan Island was designated as a special economic zone.Since then,the beau...In April of 1988,the establishment of Hainan Province was officially approved at the first session of the 7th National People’s Congress and Hainan Island was designated as a special economic zone.Since then,the beautiful Hainan Island has embraced unprecedented development opportunities and entered into a new historical stage of deepening reform and opening up economically.By virtue of continuous efforts throughout the past 30 years,Hainan has turned into an important portal for China’s reform and opening up as a frontier island.展开更多
文摘Confluences play a major role in the dynamics of networks of natural and man-made open channels, and field measurements on river confluences reveal that discordance in bed elevation is common.Studies of schematized confluences with a step at the interface between the tributary and the main channel bed reveal that bed elevation discordance is an important additional control for the confluence hydrodynamics.This study aimed to improve understanding of the influence of bed elevation discordance on the flow patterns and head losses in a right-angled confluence of an open channel with rectangular cross-sections.A large eddy simulation (LES)-based numerical model was set up and validated with experiments by others.Four configurations with different bed discordance ratios were investigated.The results confirm that, with increasing bed elevation discordance, the tributary streamlines at the confluence interface deviate less from the geometrical confluence angle, the extent of the recirculation zone (RZ) gets smaller, the ratio of the water depth upstream to that downstream of the confluence decreases, and the water level depression reduces.The bed elevation discordance also leads to the development of a large-scale structure in the lee of the step.Despite the appearance of the large-scale structure, the reduced extent of the RZ and associated changes in flow deflection/contraction reduce total head losses experienced by the main channel with an increase of the bed discordance ratio.It turns out that bed elevation discordance converts the lateral momentum from the tributary to streamwise momentum in the main channel more efficiently.
文摘The advantages of the eastern coastal economic zone and its role in the country’s economic construction as well as its relationship with the western zone are discussed.
文摘In April of 1988,the establishment of Hainan Province was officially approved at the first session of the 7th National People’s Congress and Hainan Island was designated as a special economic zone.Since then,the beautiful Hainan Island has embraced unprecedented development opportunities and entered into a new historical stage of deepening reform and opening up economically.By virtue of continuous efforts throughout the past 30 years,Hainan has turned into an important portal for China’s reform and opening up as a frontier island.
