112 / 2025-04-24 12:56:09

Prototype-Scale Physical Modelling of Two-Dimensional Scour below Pipelines in Steady Currents

Local scour is of major concern for the stability and integrity of offshore pipelines. Considerable
empirical predictive formulae on spatial and temporal development of scour below subsea
pipelines have been proposed. They have been predominantly based on data sets from
experimental studies that were often carried out through small-scale flume model tests in
laboratories with potential scale effects, i.e., discrepancies between model and prototype
responses. In the present study, physical modelling of two-dimensional scour was performed
with a prototype-scale pipeline (diameter of 0.63m) bottom-seated on cohesion-less sediment
under steady currents in a 5.0m wide, 8.0m deep, and 450m long mega flume facility. The spatial
and temporal scour development was monitored through observation window and measured by
an underwater ultrasonic ranging system. The present tests extended local scour data sets
obtained in controlled experiments from small-scale models to a prototype scale, thereby
furthering the flow field Reynolds number from sub-critical to transitional and super-critical
regimes. The present prototype-scale physical modelling aims to serve as a benchmark case for
research related to local scour below pipelines.