Numerical investigation of local scour below a vibrating pipeline under steady currents
Numerical investigation of local scour below a vibrating pipeline under steady currents
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DOI：
10.1016/j.coastaleng.2009.11.008
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发表时间：
2010-04
影响因子：
4.4
通讯作者：
Ming Zhao;Liang Cheng
中科院分区：
文献类型：
--
作者：
Ming Zhao;Liang Cheng
采用有限元数值模型对恒定水流作用下振动管道的局部冲刷进行了研究。数值模型中考虑了水流、泥沙运动和管道响应的耦合作用。冲刷深度和管道振动幅值的数值计算结果与文献中的实测数据进行了比较。取得了较好的一致性。结果表明，管道振动会增加管道下方的冲刷深度。两自由度振动管道下的冲刷坑比只沿横流方向振动的管道下的冲刷坑深。此外，还研究了水深的影响。计算结果表明，水深对冲刷深度的影响较小。然而，它确实会影响冲刷的时间尺度。水深越浅，达到冲刷平衡状态所需时间越短。研究发现，振动会迫使涡流从管道底部脱落。振动管道周围的涡流比固定管道周围的涡流更接近海床。这有助于增加冲刷深度。
Local scour below a vibrating pipeline under steady current is investigated by a finite element numerical model. The flow, sediment transport and pipeline response are coupled in the numerical model. The numerical results of scour depths and pipeline vibration amplitudes are compared with measured data available in literature. Good agreement is obtained. It is found that pipeline vibrations cause increases of scour depth below the pipeline. The scour pit underneath a two-degree-of-freedom vibrating pipeline is deeper than that under a pipeline vibrating only in the transverse flow direction. The effects of water depth are also investigated. The present numerical result shows that water depth has weak effect on the scour depth. However it does affect the time scale of the scour. The shallower the water depth is, the less time it requires to reaches the equilibrium state of scour. It is found that the vibration forces vortices to be shed from the bottom side of the pipeline. Then vortex shedding around a vibrating pipeline is closer to the seabed than vortex shedding around a fixed pipeline. This contributes to the increase of the scour depth.