Numerical Investigation of Local Scour with Inclined Piles

Abstract

In coastal and offshore engineering applications, foundations of breakwaters, offshore wind turbine foundations and piles are often damaged by local scour induced by currents or waves, which will threaten people's property and life security. The present study focuses on the local scour around cylinder piles, which are inclined toward upstream, downstream, and lateral. A vertical pile together with the three types of inclined piles was investigated by a numerical model in clear-water scour condition. Each type of the inclined pile was simulated for five inclination angles ranging from 15 degrees to 45 degrees. The angle of inclination is between the pile axis and the bed normal. By solving the Reynolds Averaged Navier-Stokes (RANS) equations, steady currents around the piles are simulated with the validated model. The results show significant differences in scour and deposition for the vertical and inclined piles. Sediments transport induced by the horseshoe vortex, contracted streamlines and the wake vortices were analyzed. Upward flow and downward flow in front of the pile were seen quite contrary between downstream inclined pile and upstream inclined pile. Local scour in lateral inclined pile was found moving toward to the inclined side. Maximum scour depth for inclined piles decreases in different degrees compared to the vertical pile.