Seminar - Bing Yang - Experimental study upon local scour of a sandy seabed around a submarine pipeline in ocean currents

Wednesday 5 September 2007, 1.10 - 1.50 pm
Civil Engineering Lecture Theatre 3

Bing Yang
Visitor at Sydney on a one year sabbatical from
Institute of Mechanics, Chinese Academy of Sciences

Abstract:
Local scour of sandy seabed around a submarine pipeline in ocean currents is a complex fluid-pipe-soil coupling problem. The similarity rules for modeling local scour of pipeline are established by means of dimensional analysis method. Physical phenomenon of local scour around the pipeline was modeled in a unidirectional flow flume. Experimental observation indicates that the process of local scour around the pipeline with an initial embedment involves four characteristic stages, i.e. spanning of pipeline, tunnel erosion, lee-wake erosion and equilibrium scouring stages. In the subcritical flow regime, there exists low correlativity between equilibrium scour depth and Reynolds number. In the case of clear-water scour, the equilibrium scour depth increases with increasing Shields number, and descends linearly with increasing initial gap-diameter ratio in the examined range of initial gap-diameter ratios (-0.25 < e₀ /D < 0.55).