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论文类型：期刊论文

发表时间：2009-04-01

发表刊物：COASTAL ENGINEERING

收录刊物：SCIE、EI

卷号：56

期号：4

页面范围：458-466

ISSN号：0378-3839

关键字：Pipeline; Onset of scour; Pressure drop coefficient; Seepage flow; Currents; Waves

摘要：A numerical model is developed to predict the onset of local scour below offshore pipelines in steady currents and waves. The scour is assumed to start when the pressure gradient underneath the pipeline exceeds the floatation gradient of the sediments. In this model, the water flow field above the bed is determined by solving the two-dimensional (2-D) Reynolds-averaged Navier-Stokes equations with a k-omega turbulence closure. The seepage flow below the seabed is calculated by solving the Darcy's law (Laplace's equation) with known pressure distribution along the common boundaries of the flow domains-seabed. The numerical method used for both the turbulent flow around the pipeline and Darcy's flow in the seabed is a fractional finite element method. The average pressure gradient along the buried pipe surface is employed in the evaluation of onset condition with a calibration coefficient The numerical model is validated against experimental data available in literature. A unified onset condition for steady currents and waves is proposed. Influences of flow parameters, including water depth, embedment depth, boundary layer thickness, Reynolds number (Re) and Keuleagan-Carpenter (KC) number, on the pressure drop coefficient over the pipeline are studied systematically. (C) 2008 Elsevier B.V. All rights reserved.