Study On The Influence Of Diversion Dikes Of Hydraulic Characteristics In Curved Branched Channel

The bending and branching shoals are one of the most common types of beach risk in the mountainous rivers in Southwest China.Because of the complicated causes of the dangerous shoals in this type of beach,the cross section of the river in the natural mountainous river is mostly complex,and the interaction of the flow of the channel flow after the flood floodplain makes the flow characteristic of the compound channel special and complicated,and the difficulty of the treatment is increased.This paper puts forward the idea of regulating the diversion dikes in the bend.The diversion dikes is actually a submerged dam.Its "diversion" function is mainly reflected in the water blocking effect of the dam body in the bend,limiting the flow of water flow from the main channel to the beach in the bend of the bend,so that the direction of the bottom flow is directed from the convex bank to the concave bank under the influence of the rotating dam,and the middle layer water is made.The diverting ratio of the reverse slope of the concave bank side is increased by the flow steering and the interface of the beach trough,which makes the bottom of the reverse slope of the concave bank side flow to the concave bank,increases the velocity of the near bottom vertical line and the turbulence intensity,so that the dispersed turbulent area in the bottom of the bottom slope gradually concentrates,making the bottom sediment movement downstream and solving the transition section shallow.The problem of beach deposition.In this paper,through the generalization of the channel shape of the convex bank branching shoal in the mountainous rivers in Southwest China,the transient numerical simulation of the 70 degree branching channel is carried out by using the RNG k-eturbulence model in Fluent and the VOF two-phase flow model,and the influence of the differentdiversion dikes schemes on the flow characteristics is studied.The following conclusions are drawn as follows:(1)The main function of the diversion dikes is to change the underflow direction of the reverse slope section under the concave side of the bank through the retaining effect of the dikes.When the length and quantity of the dikes are increased at the same time,the transfer effect of the dikes is best,and the direction of scheme four underflow is 13.7 degree deflected before the plan,which is beneficial to the concentrated erosion of the transition section of the concave bank side.(2)The Diversion dikes makes the flow field in the bend and the reverse slope redistributed,effectively enlarges the near bottom vertical flow velocity of the reverse slope below the concave bank,and the velocity of the near bottom of the reverse slope increases with the increase of the number and length of the rotating dam.The layout of the double flow dam is more conducive to the greater kinetic energy of the sediment in the bottom of the main trough side of the concave bank and to meet the start of the silt starting.Conditions.(3)The diversion dikes can effectively regulate the diversion ratio of the branch channel,and the diversion ratio of the side bank branch of the concave bank increases after the plan,which is increased by 6.5% compared with that before the plan.(4)The vertical turbulence intensity of the reverse slope section is "L" type along the water depth,and the transverse turbulence intensity distribution along the water depth can be summarized as first increasing,then decreasing and then increasing.On the whole,the lateral turbulence intensity is greater than the vertical turbulent intensity value,which is consistent with the turbulent characteristics of a single open channel.(5)The vertical turbulence intensity of the reverse slope section is "L" type along the water depth,and the transverse turbulence intensity distribution along the water depth can be summarized as first increasing,then decreasing and then increasing.On the whole,the lateral turbulence intensity is greater than the vertical turbulent intensity value,which is consistent with the turbulent characteristics of a single open channel.In this paper,the research results of the influence of the diversion dam on the flow characteristics can be directly applied to the waterway control of the Changjiang River Syrian section,and can also be used in the mountain rivers with similar conditions.It has a reference value in the river bed evolution and river regulation.