Effect of Spoilers on Wave‐Induced Scour at Submarine Pipelines

Abstract

This paper investigates the effect of spoiler orientations on wave‐induced scour around a submarine pipeline. Experiments conducted under pure wave action show that the spoiler can increase both the scour beneath (tunnel scour) and downstream of (lee‐wake scour) the pipeline. The increase in tunnel scour depth is due to the higher blockage in the flow. This high flow blockage causes the deflection of a strong flow downwards through the tunnel beneath the pipe. The lee‐wake scour depth is affected by the increase in strength of the reattached flow as flow separation occurs at the edge of the spoiler. At some spoiler orientations, the formation of a secondary hole is observed at the edge of the spoiler. Secondary scour holes form when the spoiler is located near the sediment bed. The local disturbance of flow at the edge of the spoiler is the cause of the formation of these secondary scour holes.