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Numerical Analysis of Gravity Current Flow past Subsea Pipe above a Scour

세굴된 해저 파이프 주위 중력류의 유동 해석

  • Jung, Jae Hwan (Department of Naval Architecture and Ocean Engineering, Pusan National University) ;
  • Yoon, Hyun Sik (Global Core Research Center for Ships and Offshore Plants, Pusan National University)
  • 정재환 (부산대학교 조선해양공학과) ;
  • 윤현식 (부산대학교 조선해양플랜트글로벌핵심연구센터)
  • Received : 2016.11.01
  • Accepted : 2016.12.28
  • Published : 2016.12.31

Abstract

Gravity current flow past a subsea pipe above a scour based on computational fluid dynamics. For comparison, gravity current flow over pipe above a smooth bed also calculated, this configuration conventionally employed to consider the scour effect from an ideal approach. Interestingly, there different flow features and hydrodynamic forces between the scour and smooth bed cases. These results indicate that realistic conditionvery important investigatthe scour effect on gravity current flow around subsea pipe.

본 연구에서는 세굴된 해저 파이프 주위 중력류의 유동 해석을 수행하였다. 결과 비교를 위해 세굴이 아닌 평평한 해저면 위에 틈새 거리를 두고 설치된 해저 파이프 문제를 함께 고려하였다. 여기서 세굴의 깊이와 틈새 거리는 동일하며, 평평한 해저면 위에 설치된 파이프 문제는 일반적으로 실제 세굴효과를 이상적으로 구현하기 위해 주로 고려된다. 중력류와 해저 파이프 상호작용에 대한 유동특성의 이해를 위해 농도 및 와도장, 압력장 그리고 양항력 계수 등, 다양한 물리량들을 비교 및 분석 하였다. 결과적으로 세굴과 평평한 해저면 위에 설치된 해저 파이프 주위 유동특성이 달라짐을 관찰하였다, 특히 세굴의 위 파이프의 경우 구조물 상부에서 발달된 음의 와만 하류로 나아가게 되지만 평탄면 위 파이프는 이열 와구조 형태를 가지는 것을 확인하였다. 따라서 중력류에 놓인 해저 파이프의 안전 설계를 위해서는 무엇보다 실제 세굴조건을 고려하는 것이 중요 할 것으로 판단된다.

Keywords

References

  1. Cantero, M. I., J. R. Lee, S. Balachandar and M. H. Garcia (2007), On the front velocity of gravity currents, Journal of Fluid Mechanics, Vol. 586, pp. 1-39. https://doi.org/10.1017/S0022112007005769
  2. Crank, J. and P. Nicolson(1947), A practical method for numerical evaluation of solutions of partial differential equations of the heat conduction type, Proceedings of the Cambridge Philosophical Society, Vol. 43, No. 1, pp. 50-67. https://doi.org/10.1017/S0305004100023197
  3. Ermanyuk, E. V. and N. V. Gavrilov(2005a), Interaction of an internal gravity current with an obstacle on the channel bottom, Journal of Applied Mechanics and Technical Physics, Vol. 46, No. 4, pp. 489-495. https://doi.org/10.1007/s10808-005-0100-y
  4. Ermanyuk, E. V. and N. V. Gavrilov(2005b), Interaction of an internal gravity current with a submerged circular cylinder, Journal of Applied Mechanics and Technical Physics, Vol. 46, No. 2, pp. 216-223. https://doi.org/10.1007/s10808-005-0038-0
  5. Gonzalez-Juez, E. D., E. Meiburg and G. Constantinescu (2009a), Gravity currents impinging on submerged cylinders: flow fields and associated forces, Journal of Fluid Mechanics, Vol. 631, pp. 65-102. https://doi.org/10.1017/S0022112009006740
  6. Gonzalez-Juez, E. D., E. Meiburg and G. Constantinescu (2009a), The interaction of a gravity current with a circular cylinder mounted above a wall: effect of the gap size, Journal of Fluids and Structures, Vol. 25, pp. 629-640. https://doi.org/10.1016/j.jfluidstructs.2009.01.002
  7. Gonzalez-Juez, E. D., E. Meiburg, T. Tokyay and G. Constantinescu(2010), Gravity current flow past a circular cylinder forces, wall shear stresses and implications for scour, Journal of Fluid Mechanics, Vol. 649, pp. 69-102. https://doi.org/10.1017/S002211200999334X
  8. Hairer, E., S. P. Norsett and G. Wanner(1993), Solving ordinary differential equations I: Nonstiff problems (2nd ed.), Berlin, Springer Verlag.
  9. Hofler, K. and S. Schwarzer(2000), Navier-Stokes simulation with constraint forces: finite-difference method for particle-laden flows and complex geometries, Physical Review E, Vol. 61, pp. 7146-7160. https://doi.org/10.1103/PhysRevE.61.7146
  10. Jung, J. H. and H. S. Yoon(2016), Effect of scour depth on flow around circular cylinder in gravity current, Ocean Engineering, Vol. 117, pp. 78-87. https://doi.org/10.1016/j.oceaneng.2016.03.025
  11. Kim, K. H. and H. S. Oh(2011), Comparison of local scour around pipeline caused by waves and steady currents, Journal of Ocean Engineering and Technology, Vol. 25, No. 2, pp. 21-28. https://doi.org/10.5574/KSOE.2011.25.2.021
  12. Kneller, B., S. J. Bennett and W. D. McCaffrey(1999), Velocity structure, turbulence and fluid stresses in experimental gravity currents, Journal of Geophysical Research: Oceans, Vol. 104, pp. 5381-5391. https://doi.org/10.1029/1998JC900077
  13. Liang, D. F. and L. Cheng(2005), Numerical model for wave-induced scour below a submarine pipeline, Journal of Waterway, Port, Coastal, and Ocean Engineering, Vol. 131, pp. 193-202. https://doi.org/10.1061/(ASCE)0733-950X(2005)131:5(193)
  14. Mittal, R. and S. Balachandar(1995), Effect of three-dimensionality on the lift and drag of nominally two-dimensional cylinders. Physics of Fluids, Vol. 7, No. 8, pp. 1841-1865. https://doi.org/10.1063/1.868500
  15. Sumer, B. M. and J. Fredsoe(2002), The Mechanics of Scour in the Marine Environment. World Scientific, Singapore.
  16. Sumer, B. M., J. Fredsoe, H. Gravesen and R. Bruschi(1989), Response of marine pipelines in scour trenches. Journal of Waterway, Port, Coastal, and Ocean Engineering, Vol. 115, No. 4, pp. 477-496. https://doi.org/10.1061/(ASCE)0733-950X(1989)115:4(477)
  17. Sumer, B. M., and J. Fredsoe(1990), Scour below pipelines in waves, Journal of Waterway, Port, Coastal, and Ocean Engineering, Vol. 116, pp. 307-323. https://doi.org/10.1061/(ASCE)0733-950X(1990)116:3(307)
  18. Whitehouse, R.(1998), Scour at marine structures, Thomas Telford, London, pp. 1-198.
  19. Yu, Z. and X. Shao(2007), A direct-forcing fictitious domain method for particulate flows, Journal of Computational Physics, Vol. 227, pp. 292-314. https://doi.org/10.1016/j.jcp.2007.07.027
  20. Yoon, H. S., C. H. Jeon, J. H. Jung, B. Koo, C. Choi and S. C. Shin(2013), Simulation of two-phase flow body interaction problems using direct forcing/fictitious domain level set method, International Journal for Numerical Methods in Fluids, Vol. 73, pp. 250-265. https://doi.org/10.1002/fld.3797