Investigation in water scouring of square and rectangular cross sections piles of piers perpendicular to the harbor entrance

Occurrence of water scouring phenomenon around hydraulic structures is one of the most essential factors that destroys and consequently losses of the financial each year. Existence of pier structure in front of the entrance of harbor, causes to generate three dimensional (3-D) flows around the piles of piers (due to entrance of wave into the harbor and the result of ships movements) and causes erosion, sedimentation of basin and localized water scouring. In numerical modelings that have been done so far, rate of water scouring is a function of flow parameters such as flow velocity, depth and geometrical parameters like diameter of the piles and granulation. In this paper, in addition to the study of previous parameters, we can estimate amount of affect of rotation in water scouring process around the piles of piers. In this article, according to the existence of 3-D flows around hydraulic structures such as downwards flows in front of piles and in order to consider the role of flows in water scouring a complete 3-D model is used for hydraulic flow simulation around the structures. To consider the actual boundaries of the piles of piers, the structural mesh and curvelinear border method (along the horizontal and vertical) is used. Due to changes in depth and sea bottom, the Sigma coordinate system is used to mesh.