Numerical Modeling of Local Scour below a Piggyback Pipeline in Currents
Publication: Journal of Hydraulic Engineering
Volume 134, Issue 10
Abstract
Local scour below a piggyback pipeline in steady currents is investigated numerically. A piggyback pipeline comprises two pipelines that are arranged in the so-called piggyback configuration with the small pipeline being located directly above the large pipeline. The Reynolds-averaged Navier–Stokes equations and the transport equation for suspended sediment concentration are solved using a finite element method. The bed scour profile is determined through solving sediment mass conservation equation. The numerical model is validated against experimental data available in literature on scour below a single pipeline. Computations are carried out for the diameter ratio [the small pipe diameter to the larger one ] of 0.2 and the gap ( , between the two pipelines) to the large diameter ratio ranging from 0.0 to 0.5. It is found that the flow and the scour profiles are influenced significantly by the gap ratio.
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Acknowledgments
The writers would like to acknowledge the support from the Australia Research Council through ARC Discovery Projects Program Grant No. DP0557060 and the Natural Science Foundation of China through the Joint Research Fund for Oversea Chinese Young Scholar Grant No. 50428908.
References
Allen, J. R. L. (1982). “Simple models for the shape and symmetry of tidal sand waves: I. Statically stable equilibrium forms.” Mar. Geol., 48(1–2), 31–49.
Behr, M., Johnson, A., Kennedy, J., Mittal, S., and Tezduyar, T. E. (1993). “Computation of incompressible flows with implicit finite element implementations on the connection machine.” Comput. Methods Appl. Mech. Eng., 108(1–2), 99–118.
Brooks, A. N., and Hughes, T. J. R. (1982). “Streamline upwind/Petrov-Galerkin formulations for convection dominated flows with particular emphasis on the incompressible Navier-Stokes equations.” Comput. Methods Appl. Mech. Eng., 32(1–3), 199–259.
Brørs, B. (1999). “Numerical modelling of flow and scour at pipelines.” J. Hydraul. Eng., 125(5), 511–522.
Engelund, F., and Fredsøe, J. (1976). “A sediment transport model for straight alluvial channels.” Nord. Hydrol., 7, 293–306.
Fredsøe, J., and Deigaard, R. (1992). Mechanics of coastal sediment transport, Advanced Series on Ocean Engineering, Vol. 3, Word Scientific, Singapore.
Johnson, A. A., and Tezduyar, T. E. (1994). “Mesh update strategies in parallel finite element computations of flow problems with moving boundaries and interfaces.” Comput. Methods Appl. Mech. Eng., 119(1–2), 73–94.
Li, F., and Cheng, L. (1999). “A numerical model for local scour under offshore pipelines.” J. Hydraul. Eng., 125(4), 400–406.
Li, F., and Cheng, L. (2001). “Prediction of lee-wake scouring of pipelines in currents.” J. Waterway, Port, Coastal, Ocean Eng., 127(2), 106–122.
Liang, D., Cheng, L., and Li, F. (2005). “Numerical modeling of flow and scour below a pipeline in currents. Part II: Scour simulation.” Coastal Eng., 52(1), 43–62.
Lu, L., Li, Y., and Qin, J. (2005). “Numerical simulation of the equilibrium profile of local scour around submarine pipelines based on renormalized group turbulence model.” Ocean Eng., 32(17–18), 2007–2019.
Mao, Y. (1986). “The interaction between a pipeline and an erodible bed.” Ph.D. thesis, Technical Univ. of Denmark, Lyngby, Denmark.
Menter, F. R. (1994). “Two-equation eddy-viscosity turbulence models for engineering applications.” AIAA J., 32(8), 1598–1605.
Mittal, S., Kumar, V., and Raghuvanshi, A. (1997). “Unsteady incompressible flow past two cylinders in tandem and staggered arrangements.” Int. J. Numer. Methods Fluids, 25(11), 1315–1344.
Richardson, J. F., and Zaki, W. N. (1954). “Sedimentation and fluidisation. Part I.” Trans. Inst. Chem. Eng., 32(1), 35–53.
Soulsby, R. (1997). Dynamics of marine sands, Thomas Telford, London.
Sumer, B. M., and Fredsøe, J. (2002). The mechanics of scour in the marine environment, World Scientific, Singapore.
Sumer, B. M., Jensen, H. R., and Fredsøe, J. (1988). “Effect of lee-wake on scour below pipelines in current.” J. Waterway, Port, Coastal, Ocean Eng., 114(5), 599–614.
van Rijn, L. C. (1984). “Sediment transport. Part III: Bed forms and alluvial roughness.” J. Hydraul. Eng., 110(12), 1733–1754.
van Rijn, L. C. (1987). “Mathematical modelling of morphological process in the case of suspended sediment transport.” Delft Hydraulic Communication No. 382, Delft, The Netherlands.
Wilcox, C. C. (1988). “Reassessment of the scale-determining equation for advanced turbulence models.” AIAA J., 26(11), 1299–1310.
Wilcox, D. C. (1994). “Simulation of transition with a two-equation turbulence model.” AIAA J., 32(2), 247–255.
Wu, W., Rodi, W., and Wenka, T. (2000). “3D numerical modeling of flow and sediment transport in open channels.” J. Hydraul. Eng., 126(1), 4–15.
Zhao, M., Cheng, L., Teng, B., and Dong, G. (2006). “Hydrodynamic forces on dual cylinders of different diameters in steady currents.” J. Fluids Struct., 23(1), 59–83.
Zyserman, J. A., and Fredsøe, J. (1990). “Data analysis of bed concentration of suspended sediment.” J. Hydraul. Eng., 120(9), 1021–1042.
Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 134 • Issue 10 • October 2008
Pages: 1452 - 1463
Copyright
© 2008 ASCE.
History
Received: May 10, 2006
Accepted: Feb 18, 2008
Published online: Oct 1, 2008
Published in print: Oct 2008
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