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Abstract

Offshore pipelines are buried in the seabed to be protected from the damage caused by hydrodynamic forces or by human activities. However, because of soil erosion and interaction of currents with the pipeline on the moveable seabed, the processes of local scouring and, sometimes, self-burial of pipelines take place. To increase the rate and extent of scouring, the technique of attaching a spoiler to the pipeline has been developed. In this study, two-dimensional, steady, turbulent flow around a horizontal pipeline with a spoiler near a smooth wall is investigated experimentally by using the particle image velocimetry technique. The effect of the spoiler was examined for the Reynolds numbers of Re_D=840, 1500, 4150, and 9500 based on the pipe diameter. The effect of the spoiler on the process of scouring is investigated through the parameters of the measured instantaneous and time-averaged patterns of the velocity vector field and the streamline topology. The results indicated that the attachment of the spoiler to the pipeline increases the length of the upstream and downstream separation regions and it is also observed that the spoiler does not significantly increase the rate of the flow that passes through the gap and the shear stress acting on the seabed.

Keywords

spoiler pipeline self-burial particle image velocimetry separation regions

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The flow around a pipeline with a spoiler

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