Numerical simulation of scouring downstream of horizontal apron

Abstract

One of the effective methods to reduce the kinetic energy downstream of hydraulic structures are the aprons. The horizontal aprons is one of these structures in the river that are often used downstream of stilling basins. At the time of execution, the apron and the riverbed are at the same level but when there is a flow in the boundary between the connection of the river bed and the aprons, scouring occurs, which causes the destruction of the apron and there is a possibility of destroying other water structures. In this research, using Flow 3D software, different scenarios were simulated for five Froude values of 0.32, 0.3, 0.25, 0.2, and 0.15, three Manning roughness coefficients of 0.025, 0.02, and 0.014 per particle diameter of 1.8 mm for horizontal aprons. In this numerical model, the graph of scouring depth changes in relation to Froude numbers in different roughness coefficients, the effect of Froude numbers on the location of the scour hole for different roughness coefficients of the horizontal aprons, the shear stress changes in relation to the length of the horizontal aprons with different roughness coefficients and different Froude numbers, as well as Erosion changes with respect to the length of the horizontal aprons were calculated with different roughness coefficients and different Froude numbers.

Keywords

• manning’s roughness coefficient
• shear stress
• horizontal apron
• flow 3d
• bed depth
• sediment load