Experimental Study On The 3D Turbulence Flow Of The River Channel With Deposits

In the alpine canyon area,due to collapse,landslides and debris flow and other geological disasters,it is easy to produce loose body into the river to form the general flow conditions difficult to carry the deposit.These deposits will increase the source of river sediment,squeeze the flow path,change the movement characteristics of the river flow and sediment transport characteristics.The turbulence characteristics of river flow under the effect of deposit,which can provide theoretical support for river bed evolution and embankment design.It can also lay a theoretical foundation for studying the related research of sediment transport and sedimentation.The method of theoretical analysis and experimental study is used in this paper.The data were collected by the Acoustic Doppler Velocimetry(ADV).The influence of different flow,the lateral width ratio and lateral slopes of the deposits on the three-dimensional flow velocity,turbulent energy and three-dimensional turbulence intensity of the flow are studied.The main research results are as follows:(1)The distribution of three-dimensional flow velocity in the survey area was studied.Affected by the fan-shaped boundary of the deposit,a circulation flow is generated in the water,and the lateral flow velocity is reversed.As the depth of water increases,the deflection of the water flow gradually shifts from the right bank to the left bank.Because the shape of the deposit,the underlying water flow deflects sharply.In the downstream section of the deposit,there is spiral flow in the upward and downward direction in the flow.In this case,the flow of the river is similar to the flow of the curve,and it is easy to cause the phenomenon of left-right siltation and uneven distribution of the sediment in the river bed.The circulation axis(v = 0)gradually leans along.Before recovery of the overcurrent section,the w flow rate peaked near the circulation axis.At a small flow rate,the deposit has the greatest influence on the three-dimensional flow velocity.The lateral width ratio and the lateral slope of the deposit have similar effects on the lateral distribution of the longitudinal flow velocity,and have slightly different effects on the transverse flow velocity and the vertical flow velocity.(2)The change law of the turbulent energy in the survey area was analyzed.Upstream of the deposit,the turbulent energy is minimal.The turbulent energy in the deposit section began to increase.The strong turbulence zone is 0 to 2 relative distance from the deposit.Downstream,the turbulent energy of the water begins to decrease,but its value is still greater than the turbulent energy upstream of the deposit.As the water depth increases,the turbulent energy increases,and the strong turbulence zone changes from the left bank to the right bank in the downstream reflow area of the deposit.With the increase of the flow rate,the turbulence energy increases first and then decreases.The range of strong turbulence zones increases with increasing flow rates and moves downstream.As the lateral width ratio and the lateral slope of the deposit increase,the strong turbulence area of the water flow from the left bank reversal area to the right bank of the deposit.(3)The distribution of three-dimensional turbulence intensity in three dimensions was analyzed.Three-way turbulent intensity changes: ?u ?v ?w The three-way turbulent intensity is similarly distributed along the cross section.The left,middle,and right lines are similarly distributed.Along vertical changes,longitudinal turbulence intensity and transverse turbulence intensity are consistent,and vertical turbulence intensity is slightly different.The upstream is mainly affected by hydrophobic water,and the turbulence of water is weak.The turbulence intensity is evenly distributed along the depth and horizontal.In the river of the deposit,the deposit has the greatest effect on the beam narrowing of the water flow.At this time,the turbulence of the water flow becomes stronger,and the turbulence intensity of the water flow increases suddenly near the bottom layer and the surface layer.As the distance from the deposit gets closer,the upstream is affected by the deposit to generate lateral flow.The turbulence of water is strengthened,and the turbulent energy-enhanced region mainly occurs near the boundary of the deposit,and the nearer the distance from the deposit,the stronger the turbulence intensity of the water flow.The reason for this phenomenon may be related to the Karman vortex occurring near the boundary of the deposit.The maximum value of turbulent intensity is obtained downstream,and the turbulent intensity begins to gradually decrease as the distance from the deposit increases,but the value is still greater than the upstream turbulence intensity.Downstream of the deposit,the pulsation on the left side of the flow gradually decreases with the distance from the deposit,and eventually reaches the level of the right bank,but the overall value of the downstream turbulence intensity is still higher than the upstream turbulence intensity.Flow,lateral width ratio and lateral slopes of the deposit will affect the three-way distribution of turbulence intensity.Including the lateral width ratio of the deposit and the lateral slopes has the similar effect on the turbulence intensity,but the influence of the lateral width ratio is greater than that of the lateral slope.