Abstract
Design dependencies to determine the velocity and concentration of suspended matter in the swirling zone beyond the transverse dam in the presence of the initial section of the jet are proposed in the article, using the main provisions of the theory of turbulent jets, the scheme of dividing the flow into hydraulic homogeneous zones: a weakly perturbed core, intense turbulent mixing and reverse currents. The distribution of velocities and concentration of suspended matter (turbidity) in the zone of intense turbulent mixing are affine and obey the theoretical Schlichting-Abramovich relationships; this was substantiated by laboratory and field studies. The equations of continuity and conservation of solid matter along the flow were used to solve the problem. To establish the adequacy of the dependencies obtained, a test problem was implemented in which the velocities in the core and the depth along the flow were assumed constant. The problem was implemented for the following contraction ratios of flow nc 0,1; 0.2; 0.3; 0.4; 0.5. Tabular and graphic dependencies obtained show that with all contraction ratios of flow, the relative backflow velocities first increase, and at the end of the swirling zone, they sharply decrease. The maximum is observed at the intersection of the outer boundary of the zone of intense turbulent mixing with the protected coast and reaches m = 0.317. Comparison of the calculation results with the experimental ones shows their qualitative and quantitative agreement. The relative concentration of suspended matter in reverse currents remains practically constant along the entire length of the swirling zone. It is close to unity for all contraction ratios of flow.
Highlights
The acute shortage of water and land resources in Uzbekistan and other republics of Central Asia raised the question of the development of fertile floodplain lands [1, 2]
The studies conducted earlier have established the affinity of the velocity field in the zone of intense turbulent mixing (Fig. 1), which obeys the theoretical Schlichting-Abramovich dependence [19, 20], and has the following form for the initial section of the jet (Fig. 1)
Since lowland rivers carry a large amount of suspended sediment, as shown by field observations conducted on the Amu Darya River [18], a certain part of the suspended sediment settles in the swirling zone between the dams (Fig. 1)
Summary
The acute shortage of water and land resources in Uzbekistan and other republics of Central Asia raised the question of the development of fertile floodplain lands [1, 2]. The formation of solid runoff in the river basin, transportation, and channel processes, sedimentation of suspended matters on the floodplains and deltaic parts of rivers is of great interest to scientists worldwide [3,4,5,6,7]. Transverse dams contracting the river channel were used as regulatory structures [11, 12]. In the process of interaction with the flow beyond the dams, intensive siltation of the space between the dams occurs [16,17,18]. The forecast of sedimentation in the inter-dam space remains poorly understood
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