Numerical investigation of the influence of the small pipeline on local scour morphology around the piggyback pipeline. (15th November 2021)

• Record Type: Journal Article
• Authors: Yang, Shaopeng; Guo, Yakun; Shi, Bing; Yu, Guoliang; Yang, Lipeng; Zhang, Mingxi
• Is Part Of: Ocean engineering. Volume 240(2021)
• Publication Date: 2021-11-15
• Subjects: Piggyback pipelines -- Position angle -- Scour -- Steady flow -- Numerical models -- Hydrodynamic forces; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2021.109973
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: This paper presents the results from a numerical simulation study to investigate the effect of the position angle ( α ) of small pipeline on the local scour and the hydrodynamic force around the piggyback pipeline in steady current conditions. Results show that the local scour depth around the piggyback pipeline increases first and then decreases with the increase of α . The scour depth and width reach the maximum values as the small pipe locates at the top of the large pipeline (i.e. α = 90°). The scour around the piggyback pipeline is accelerated when α ranges between 30° and 165°, while for α = 0°–30° and 165°–180°, the local scour around the piggyback pipeline is inhibited. Furthermore, the small pipe placed in front of the large pipe has slightly larger effect on the scour hole morphology than that when it is placed behind the large pipe. The drag force coefficient increases first and reaches the maximum value at α = 75°, and then decreases with the increase of α. Eventually the drag force coefficient approaches roughly a constant. The lift force coefficient is approximately a V-shaped with the variation of α and has the maximum value at α = 90°. Highlights: Local scour and hydrodynamic forces around piggyback pipeline are affected by the position angle of the small pipeline. Scour around piggyback pipeline is accelerated for α = 30°–165° and is inhitited for other position angles. Small pipe placed in front of large pipe has greater effect on scour morphology than that when placed behind.