Experimental study of local scour around piles in tidal current

![CDATA[This paper presents an experimental study of local scour around a vertical circular pile subject to unidirectional flow, sinusoidal tidal current and a reversing current (i.e. a ‘square’ tide). The scour depth around the model pile was continuously measured using a pair of Contact Image Sensors (CIS) with high spacial resolution and sampling frequency. The test results show that the equilibrium scour depth induced by tidal current is slightly smaller than that induced by a unidirectional flow with a velocity equal to the peak velocity of the tidal current. Since backfilling occurs on the downstream side of the pile after flow reversal in tidal current tests, the measured scour depth fluctuates with the same frequency as the tidal current. The three-dimensional (3D) scour profiles were measured with an infrared 3D scanner, providing detailed information on the extent of scour around the pile.]]