往复流作用下海底管线冲刷模拟研究

Numerical study on scour around offshore pipeline in reciprocating tidal flow

海底管线冲刷悬空是诱发管道涡激振动破坏的一个主要原因。为更好地对管线冲刷悬空情况进行评估,本文应用水动力-泥沙冲刷耦合模型,对往复潮流作用淤泥质海床海底管线局部冲刷过程进行了模拟研究,模型采用标准k-ε紊流方程对N-S方程进行封闭,控制方程采用有限差分法进行离散,模拟结果表明,双向潮流作用下,管道局部冲刷轮廓基本呈现对称状态,其最大冲刷深度位置因水流流速的转向而有所摆动,往复流引起的冲刷深度较恒定流情况减小约20%左右。

Suspension of offshore pipeline due to seabed scour is the main factor which induces the vortex vi- bration of pipeline. In order to elevate the scour characteristics of offshore pipeline, the scour below offshore pipeline on muddy bed in reciprocating tidal flow was studied by a coupled numerical model, Flow-3D, which includes the hydrodynamics and sediment transport model. The standard k-ε equations were used to close the N-S equations and the governing equations were discretized by finite difference method. The numerical results show that the scour profile is nearly symmetry under reversal tidal flow. The position of maximum scour depth fluctuates during the scouring process. Besides, the maximum scour depth under reversal tidal flow is smaller than the value under steady current by 20%.