Experimental study on local scour characteristics around an upstream inclined pile under combined wave and current action

In the context of wave-current, the characteristics of vortex structure and wave propagation around the upstream inclined pile differ significantly than around the vertical pile, which affects the local scour process of the pile foundation. To better understand the characteristic of local scour around upstream inclined piles under the joint action of wave and current, local scour tests were carried out in the wave-current flume for the upstream inclined piles with different inclination angles. Besides, a preliminary investigation was conducted into the ephemeral characteristics of local scour depth, influencing factors, and the characteristics of bed morphology. As suggested by the research results, the local scour depth of upstream inclined piles is smaller compared to vertical piles under the context of clear water scour at all times. The equilibrium scour depth decreases progressively, and the relative time scale (T₀^*)shows an incremental increase when the pile inclination rises. Besides, the width of scour hole is smaller compared to vertical piles, showing a teardrop-like shape, while the dune after the tail exhibits a longer single-peaked band structure with a more significant irregularity. Despite a close correlation between the depth of local scour and Froude number, the wave deformation caused by upstream inclination makes it more difficult to determine the specific function of scour depth, radio of velocities and Keulegan-Carpenter number.