Hydraulic Characteristics Study On Wake Of Submarine Pipeline Under The Actions Of Tidal Current

The submarine pipeline is the most important oil transport tool in ocean oilexploitation. It is an indispensable component in offshore oil production systems.Because the ocean environment is very complicated, the influences of many uncertainfactors make it very difficult to lay and manage underwater pipelines. Along with theexploitation of deep ocean oil, the application of submarine pipeline has becomeincreasingly widespread. Hence more and more attention is being paid to the erosionand destruction problems caused by ocean dynamics.In this paper, the flow mechanism near pipelines is analyzed and the back-flowregion around the submarine pipelines in unidirectional flow was divided into3areas(reverse flow region、free shear region and core region) along depth. According tocharacteristic in the free shear region and with the similar method for analyzing jets,the velocity profiles in the free shear region through properly simplifying thegoverning equations are presented. According to the distribution characteristic of theflux, the calculated formula of the back-flow region length is presented.A systematic experimental research on the characteristics of the flow velocityfield around the submarine pipelines was conducted by ADV. Based on the obtainedexperimenta1data，the rules of velocity and turbulent intensity changes in differentareas were also investigated. Comparisons of the theoretical analysis with experimentsshow that the approach is successful. Besides theoretical research and experimentalinvestigation above-mentioned, a vertical two-dimensional numerical model was usedto simulate the back-flow region around the submarine pipelines to unidirectionalsteady flow. The results computed by the model agree well with the measure results.The study of this paper makes a theoretic foundation for deepen discussing thetheory of the submarine pipeline be scoured and protection technique.