Time Scale For Wave/Current Scour Below Pipelines

Abstract

A non-dimensional formula has been developed for the time scale of the scour process below a marine pipeline, based on the presently available data. The main part of the data originates from ISVA. Both the current case and the pure-wave case are considered. The results indicate that the non-dimensional time scale is proportional to the -5/3 power of the Shields parameter. In the study, the time scale of scour, involving a change in the wave climate has also been investigated. The results indicate that the time scale is governed by the Shields parameter plus the two Keulegan-Carpenter numbers corresponding to the waves before and after the change takes place.