Numerical Study on the Effect of Protective Structures on Scouring due to Dam Break Using a Two-phase Lagrangian Model

Scouring depth due to dam break flows as one of the important engineering problems can be investigated numerically by means of an appropriate multiphase model. Smoothed Particle Hydrodynamic (SPH) model is a Lagrangian Mesh-free based method that has been introduced to solve such complicated flows.

A Multiphase version of this model is modified in this study to predict scouring depth after dam break flows. At first, the introduced model is validated via comparing the results with experimental data and it is confirmed that the model can well predict turbulent multiphase flows. Then, the performance of a scour protection structure with different length and heights is simulated against dam break flow to find an optimum geometry for this structure.

Based on the results, it is concluded that the effect of structure height on scour reduction is more sensible than the effect of structure length. In contrast to the structure length, a small edge at the end of the protective structure can efficiently decrease the final scoured depth. However, there exists an optimum height with the best performance. A too high scour protection structure can even result in a higher scouring depth than an unprotected case. Therefore, it is necessary to use a protection structure with an appropriate height and the introduced model can be utilized as a helpful tool to check the required performance of this structure.