Effect of bed vicinity on vortex shedding and force coefficients of fluid flow on an offshore pipeline

Abstract

The effect of rigid bed proximity on flow parameters and hydrodynamic loads in offshore pipelines exposed to turbulent flow is investigated numerically. The Galerkin finite volume method is employed to solve the unsteady incompressible 2D Navier–Stokes equations. The large eddy simulation turbulence model is solved using the artificial compressibility method and dual time-stepping approach. The proposed algorithm is developed for a wide range of turbulent flows with Reynolds numbers of 9500 to 1.5×10⁴. Evaluation of the developed numerical model shows that the proposed technique is capable of properly predicting hydrodynamic forces and simulating the flow pattern. The obtained results show that the lift and drag coefficients are strongly affected by the gap ratio. The mean drag coefficient slightly increases as the gap ratio increases, although the mean lift coefficient rapidly decreases. The vortex shedding suppression happen at the gap ratio of less than 0.2.

Keywords

Navier–Stokes equations / artificial compressibility method / dual time stepping / gap ratio / flat seabed / offshore pipelines / vortex shedding

References

[1] Ai Y, Feng D, Ye H, Li L. Unsteady numerical simulation of flow around 2-D circular cylinder for high Reynolds numbers. Journal of Marine Science and Application, 2013, 12(2): 180-184

[2] Bearman P, Zdravkovich M. Flow around a circular cylinder near a plane boundary. Journal of Fluid Mechanics, 1978, 89(1): 33-47

[3] Buresti G, Launaro F. Pressure measurements around a circular cylinder in cross flow near a plane boundary, 1980, 1-101

[4] Chorin AJ. A numerical method for solving incompressible viscous flow problems. Journal of Computational Physics, 1967, 2(1): 12-26

[5] Gao FP, Yang B, Wu YX, Yan SM. Steady current induced seabed scour around a vibrating pipeline. Applied Ocean Research, 2006, 28(5): 291-298

[6] Jensen B, Sumer B, Jensen H, Fredsoe J. Flow around and forces on a pipeline near a scoured bed in steady current. Journal of Offshore Mechanics and Arctic Engineering, 1990, 112(3): 206-213

[7] Kazeminezhad M, Yeganeh-Bakhtiary A, Etemad-Shahidi A. Numerical investigation of boundary layer effects on vortex shedding frequency and forces acting upon marine pipeline. Applied Ocean Research, 2010, 32(4): 460-470

[8] Kiya M. Study on the turbulent shear flow past a circular cylinder. Bulletin of the Faculty of Engineering, Hokkaido University, 1968, 50: 1-101

[9] Lee YG, Hong SW, Kang KJ. A numerical simulation of vortex motion behind a circular cylinder above a horizontal plane boundary. The Fourth International Offshore and Polar Engineering Conference, 1994, 428-433

[10] Lei C, Cheng L, Armfield S, Kavanagh K. Vortex shedding suppression for flow over a circular cylinder near a plane boundary. Ocean Engineering, 2000, 27(10): 1109-1127

[11] Li Y, Chen B, Lai G. The numerical simulation of wave forces on seabed pipeline by three-step finite element method and large eddy simulation. The Seventh International Offshore and Polar Engineering Conference, 1997, 273-277

[12] Liang D, Cheng L. Numerical modeling of flow and scour below a pipeline in currents: Part I. Flow simulation. Coastal Engineering, 2005, 52(1): 25-42

[13] Namazi-Saleh F, John KV, Mustaffa ZB. Numerical evaluation of galerkin finite volume solver for laminar/turbulent flow over flat plate. ARPN Journal of Engineering and Applied Sciences, 2016, 11(4): 2393-2399

[14] Namazi-Saleh F, Kurian JV, Zahiraniza MB. Investigation of vortex induced vibration of offshore pipelines near seabed. Applied Mechanics and Materials, 2014, 567: 265-270

[15] Oner AA, Kirkgoz MS, Akoz MS. Interaction of a current with a circular cylinder near a rigid bed. Ocean Engineering, 2008, 35(14): 1492-1504

[16] Ong MC, Utnes T, Holmedal LE, Myrhaug D, Pettersen B. Numerical simulation of flow around a circular cylinder close to a flat seabed at high Reynolds numbers using a k–e model. Coastal Engineering, 2010, 57(10): 931-947

[17] Roshko A, Steinolfson A, Chattoorgoon V. Flow forces on a cylinder near a wall or near another cylinder, 1975

[18] Sabbagh-Yazd R, Mastorakis N, Meysami F, Namazi-Saleh F. 2D Galerkin finite volume solution of steady inviscid/viscous/turbulent artificial compressible flow on triangular meshes. International Journal of Computers, 2008, 2(1): 39-46

[19] Sohankar A. Large eddy simulation of flow past rectangular-section cylinders: Side ratio effects. Journal of Wind Engineering and Industrial Aerodynamics, 2008, 96(5): 640-655

[20] Zhao X, Zhang S, Meganathan A. Implicit time accurate method for unsteady computations. 47th Aerospace Sciences Meeting and Exhibit, 2009