Turbidity current, one of the most frequent marine geological disasters, has a strong influence on ocean structures due to its high speed, frequent occurrence, wide occurrence, and long-distance transport. In this study, the effect of turbidity current on hydrodynamic characteristics of submarine pipeline is studied by considering the pipeline diameter, pipeline suspension height, pipeline location, and the gap between two pipelines. Based on computational fluid mechanics, a fluid model and a sediment transport model are established. The area and volume fractions of the sediment particles are calculated depending on the fractional volume method to fully couple the submarine pipeline and turbidity current in the fluid domain. The results show that when the turbidity current impinges on the pipeline, the vortex shedding occurs downstream of the pipeline and the dynamic response of rising and fluctuating occurs twice, in which the turbidity current head has more influence than the main body. With the increase of pipeline diameter, the hydrodynamic response of pipe increases. With the increase of the suspension height, the turbidity current around the pipeline changes from asymmetric to symmetric, and the hydrodynamic fluctuation of the pipeline increases. As the gap between pipeline and turbidity current increases, vortex shedding and hydrodynamic response caused by the main body of turbidity current increase. In the tandem pipelines case, the flow and hydrodynamic forces of the downstream pipeline are more complex but the hydrodynamic forces are smaller than in the single pipeline case. It is anticipated that the findings in this paper will enhance our understanding on the damage mechanism of the submarine pipeline by turbidity current and may also be useful in future design practices of pipelines.

Turbidity current,Submarine pipeline,Flow characteristics,Hydrodynamic response,Numerical simulation