We conducted a series of physical experiments to investigate time scale of local scour below a subsea pipeline under changing flow condition.
In this study, two consecutive flow conditions and uniform increasing flow conditions and backfill process are considered.
Different arrangements of two consecutive flow conditions, and the ramp-up current flow, wave flow and combined waves and current flow are all considered.
The algorithm to accumulate the effects of the different flow conditions is described based on recent proposed time scale formulae and present experimental data.
The results show that the present method gives a good agreement with the measured data.