Numerical Study of Simultaneous Effect of the Sidewall Slope and the Geometric Shape of Reservoir on the Flood Characteristics Caused by Dam Break on Dry Bed Condition

Dams are structures that, despite environmental impacts, are built primarily to provide water and energy. The failure of the dam creates a huge current that follows the flood in the downstream areas. For this reason, determining the characteristics of the dam failure current, including the depth of flow and the speed of wave propagation, is of great importance. In this study, the simultaneous effect of the geometric shape of the reservoir on the plan and slope of the sidewall of the reservoir on the pattern and how the flood wave caused by the failure of the dam was performed in a three-dimensional numerical modeling using Flow3D software. For this purpose, four different reservoir shapes were used in the plan, including a wide, trapezoidal, L-shaped and long reservoir with sidewall slopes of 30, 45, 60 and 90 °, taking into account the downstream dry bed. The results of three-dimensional numerical modeling showed that in all studied reservoirs, by decreasing the lateral slope of the reservoir wall, water level fluctuations increased due to the formation of two negative waves that spread on the slope of the reservoir wall and reached the central line of the reservoirs. Moreover, the effect of the geometric shape of wide and trapezoidal reservoirs on the flow characteristics due to dam failure was greater than the effect of reducing the slope of the sidewall of these reservoirs. While in long and L-shaped reservoirs, reducing the slope of the sidewall of these tanks has a great effect on the flow characteristics due to dam failure.