On the scour characteristics of submarine flexible cable in three-dimensional flow

Submarine flexible cables play a crucial role in transmitting global telecommunications and power. Failure of these flexible cables could cause significant economic loss. Most previous studies focused on scouring around the rigid pipelines and less attention has been paid to investigating the scouring around the flexible cable. In this study, fifty-six laboratory experiments, covering a wide range of flow and cable conditions, are conducted to investigate the scouring process around the submarine flexible cable. The experiments consider the perpendicular flow to the flexible cable. Results indicate that seepage is the vital factor for initiating sediment transport and scouring around the flexible cable. Opposing rotational and transverse vortices are formed downstream of the cable during scouring. When cable lays on the bed surface (i.e., the embedment depth is zero), an almost constant lateral scour development rate V h is observed and measured. Experiments demonstrate that when the cable is buried, both V h and scour depth are affected by the embedment depth and flow strength . Self-burial phenomenon may occur in the high flow strength with a small embedment depth ratio. • Three-dimensional scour characteristics around submarine flexible cable in steady currents are investigated using laboratory experiments. • Vibration and deformation of the flexible cable affect the sediment transport and scour around the cable, which differs from the rigid pipeline. • Seepage is a vital factor for initiating sediment transport and scouring around the flexible cable. • The effect of cable embedment depths on the scouring process is assessed. • The evolution of lateral scour development rate, time-dependent scour depth, and equilibrium scour state are investigated and analyzed.