考虑波浪自由表面作用的海底管道局部泥沙冲刷数值研究

Numerical Investigation of Local Scour Around Pipeline under Surface Waves

该文利用有限元方法,在任意拉格朗日-欧拉(Arbitrary Lagrangian-Eulerian,ALE)观点下求解不可压缩粘性流体的Navier-Stokes方程和泥沙输运方程,建立了可充分考虑波浪自由表面影响作用的海底管道局部冲刷数值分析模型。其中,流动的湍流效应通过SST k?ω模型进行模拟,波浪自由表面及底床变形通过动网格方法进行实时界面追踪,模型同时考虑了悬移质输沙和推移质输沙。通过与已发表研究成果的对比验证,该文所建立的模型具有良好的数值精度。在进一步考虑波浪自由表面效应的基础上,对海底管道局部冲刷问题开展了数值研究,考察了入射波高和波浪周期对局部冲刷以及管道受力的影响作用。该文所建立的数值模型是对以往长期采用简化的振荡流模型(忽略波浪自由表面效应)进行海底管道局部冲刷数值研究的重要发展。

A two-dimensional finite element numerical model is developed to predict the local scour around submarine pipelines induced by orbital fluid motion of surface water waves.The numerical model is based on the two-dimensional Navier-Stokes equations with ShearStress Transport(SST)k-ω turbulent closure.Both suspended load and bed load sediment transportations are considered.The moving boundaries of wave free surface and the evolution of the seabed due to local scour are tracked by using Arbitrary Lagrangian-Eulerian(ALE)method.Comparisons with available theoretical and experimental data show satisfactory agreements.The proposed numerical model is then used to investigate the nonlinear wave-induced local scour around pipelines.The effects of wave height and wave period on the local scour and the wave forces on the pipelines are examined.The present numerical model is a further development for the investigation of local scour around pipeline compared with oscillatory flow model.