Mechanics of Three-Dimensional Pipeline Scour in Unidirectional Steady Current

Abstract

The three-dimensional flow velocity components at the span shoulder, which is located at the junction of a submarine pipeline and the associated scour hole, are measured in unidirectional steady current in order to investigate the flow structure and mechanics of the lateral propagation of a three-dimensional pipeline-scour hole. A naturally formed three-dimensional scour hole around a modeled pipeline is immobilized using adhesive, giving a steady flow field around the fixed boundary. A three-dimensional down-looking acoustic Doppler velocimeter is then used to measure the flow velocities at several critical sections. Combined with the measured data and observations made in the study, the flow characteristics and other factors that affect propagation of the three-dimensional pipeline-scour hole in steady current are discussed.