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Numerical modeling of secondary flow behavior in a meandering channel with submerged vanes

잠긴수제가 설치된 만곡수로에서의 이차류 거동 수치모의

  • Lee, Jung Seop (Department of Civil Engineering, Gangnueng-Wonju National University) ;
  • Park, Sang Deog (Department of Civil Engineering, Gangnueng-Wonju National University) ;
  • Choi, Cheol Hee (Department, Korea Engineering Consultants Corps.) ;
  • Paik, Joongcheol (Department of Civil Engineering, Gangnueng-Wonju National University)
  • 이정섭 (강릉원주대학교 공과대학 토목공학과) ;
  • 박상덕 (강릉원주대학교 공과대학 토목공학과) ;
  • 최철희 ((주)한국종합기술 수자원부) ;
  • 백중철 (강릉원주대학교 공과대학 토목공학과)
  • Received : 2019.08.12
  • Accepted : 2019.10.02
  • Published : 2019.10.31

Abstract

The flow in the meandering channel is characterized by the spiral motion of secondary currents that typically cause the erosion along the outer bank. Hydraulic structures, such as spur dike and groyne, are commonly installed on the channel bottom near the outer bank to mitigate the strength of secondary currents. This study is to investigate the effects of submerged vanes installed in a $90^{\circ}$ meandering channel on the development of secondary currents through three-dimensional numerical modeling using the hybrid RANS/LES method for turbulence and the volume of fluid method, based on OpenFOAM open source toolbox, for capturing the free surface at the Froude number of 0.43. We employ the second-order-accurate finite volume methods in the space and time for the numerical modeling and compare numerical results with experimental measurements for evaluating the numerical predictions. Numerical results show that the present simulations well reproduce the experimental measurements, in terms of the time-averaged streamwise velocity and secondary velocity vector fields in the bend with submerged vanes. The computed flow fields reveal that the streamwise velocity near the bed along the outer bank at the end section of bend dramatically decrease by one third of mean velocity after the installation of vanes, which support that submerged vanes mitigate the strength of primary secondary flow and are helpful for the channel stability along the outer bank. The flow between the top of vanes and the free surface accelerates and the maximum velocity of free surface flow near the flow impingement along the outer bank increases about 20% due to the installation of submerged vanes. Numerical solutions show the formations of the horseshoe vortices at the front of vanes and the lee wakes behind the vanes, which are responsible for strong local scour around vanes. Additional study on the shapes and arrangement of vanes is required for mitigate the local scour.

만곡수로에서의 흐름은 나선형 운동 형태의 이차류가 지배적이며, 이로 인해 일반적으로 만곡 외측을 따라 침식 현상이 발생하게 된다. 이러한 이차류를 약화시키기 위해서 보통 만곡수로 외측을 따라서 수제와 같은 수공구조물을 설치한다. 이 연구에서는 OpenFOAM 오프소스 소프트웨어를 토대로 난류 해석을 위한 하이브리드 RANS/LES 기법과 자유수면 해석을 위한 VoF기법을 이용한 3차원 수치모의를 통해서 $90^{\circ}$ 만곡수로에 설치된 잠긴수제가 후루드수가 0.43인 조건에서 이차류의 발달에 미치는 영향을 분석하였다. 시간과 공간에 대해서 2차 정확도의 유한체적법을 이용하여 수치모의를 수행하였으며, 수치해석 결과는 실험결과와 비교하여 수치모의의 정확도를 평가하였다. 잠긴수제가 설치된 경우의 수치모의 결과를 흐름방향 유속 분포와 횡방향 순환 유속벡터장을 중심으로 수리실험 관측값들과 비교할 때 수치모의 결과는 수리실험에서 관측된 주요 이차류 흐름 거동과 현상들을 대부분 양호한 정확도로 잘 재현하는 것으로 나타났다. 수치모의 결과를 비교해보면, 잠긴수제 설치로 인해서 만곡이 끝나는 단면 외측 하상부근에서의 유속은 약 평균유속의 1/3 정도 감소하는 반면에 수제 상단부에서의 전단층 발달에 따른 흐름 가속으로 자유수면 부근까지 유속이 증가하고 만곡 수충부에서는 수면 부근 유속이 약 20% 증가하는 것으로 나타났다. 결과적으로 잠긴수제는 만곡부에서 발생하는 이차류의 강도를 약화시켜 만곡부 외측 하상의 안정에 도움이 될 것으로 판단된다. 한편, 각 잠긴수제 전면부에서 말발굽와가 그리고 후면부에서는 후류가 형성되면서 수제 구조물 주변에서 강한 국부세굴이 발생하는 것으로 나타남으로, 국부세굴을 최소화할 수 있는 수제의 형상 및 배열에 대한 추가 연구가 요구된다.

Keywords

References

  1. Abad, J. D., Erias, C. E., Buscaglia, G. C., and Garcia, M. H. (2013). "Modulation of the flow structure by progressive bedforms in the Kinoshita meandering channel." Earth Surface Processes and Lansforms, Vol. 38, No. 13, pp. 1612-1622.
  2. Barani, G. A., and Sardo, M. S. (2013). "Experimental investigation of submerged vanes' shape effects on river-bend stability." Journal of Hydraulic Structures, Vol. 1, No. 1, pp. 37-43.
  3. Biedenharn, D. S., Elliot, C. M., and Watson, C. C. (1997). The WES stream investigation and streambank stabilization handbook. U.S. Army Corps of Engineers, Vicksburg, Miss.
  4. Blanckaert, K. (2009). "Saturation of curvature-induced secondary flow, energy losses, and turbulence in sharp open-channel bends: Laboratory experiments, analysis, and modeling." Journal of Geophysical Research, Vol. 114, No. F3, p. F03015. https://doi.org/10.1029/2008JF001137
  5. Blanckaert, K., and de Vriend, H. J. (2004). "Secondary flow in sharp open-channel bends." Journal of Fluid Mechanics, Vol. 498, pp. 353-380. https://doi.org/10.1017/S0022112003006979
  6. Constantinescu, G., Koken, M., and Zeng, J. (2011). "The structure of turbulent flow in an open channel bend of strong curvature with deformed bed: Insight provided by detached eddy simulation." Water Resources Research, Vol. 47, No. 5, p. W05515. https://doi.org/10.1029/2010WR010114
  7. Deshpande, S. S., Anumolu, L., and Trujillo, M. (2012). "Evaluating the performance of the two-phase flow solver interFoam." Computational Science and Discovery, Vol. 5, No. 1, p. 014016. https://doi.org/10.1088/1749-4699/5/1/014016
  8. Flockstra, C. (2006). "Modelling of submerged vanes." Journal of Hydraulic Research, Vol. 44, No. 5, pp. 591-602. https://doi.org/10.1080/00221686.2006.9521709
  9. Gritskevich, M. S., Garbaruk, A. V., Schutze, J., and Menter F. R. (2012). "Development of DDES and IDDES formulations for the k-${\omega}$ shear stress transport model." Flow Turbulence and Combustion, Vol. 88, No. 3, pp. 431-449. https://doi.org/10.1007/s10494-011-9378-4
  10. Jia, Y., Scott, S., Xu, Y. C., Huang, S. L., and Wang, S. S. Y. (2005). "Three-dimensional numerical simulation and analysis of flows around a submerged weir in a channel bendway." Journal of Hydraulic Engineering, Vol. 131. No. 8, pp. 682-693. https://doi.org/10.1061/(ASCE)0733-9429(2005)131:8(682)
  11. Kim, S. J., Kang, J. G., and Yeo, H. K. (2014). "An experimental study on flow characteristics for optimal spacing suggestion of $45^{\circ}$ upward groynes." Journal of Korea Water Resources Research, Vo. 47, No. 5, pp. 459-468.
  12. Koken, M., and Constantinescu, G. (2014). "Flow and turbulence structure around abutments with sloped sidewalls." Journal of Hydraulic Engineering, Vol. 140, No. 7, p. 04014031. https://doi.org/10.1061/(ASCE)HY.1943-7900.0000876
  13. Lee, D. H., Kim, S. J., and Kang, S. (2015). "An experimental study on the effect of a hydraulic structure on the three-dimensional flow in a meandering channel." Journal of Korea Water Resources Research, Vol. 48, No. 8, pp. 635-645.
  14. Lee, J., Jeon, J., Kim, Y., and Kang, S. (2018). "Flume experiments for studying the effects of submergence on three-dimensional flow structure around a spur dike." Journal of Korea Water Resources Research, Vo. 51, No. 2, pp. 109-120.
  15. Marelius, F., and Sinha, S. (1998). "Experimental investigation of flow past submerged vanes." Journal of Hydraulic Engineering, Vol. 124, No. 5, pp. 542-545. https://doi.org/10.1061/(ASCE)0733-9429(1998)124:5(542)
  16. Menter, F. R. (1994). "Two-equation eddy-viscosity turbulence models for engineering applications." AIAA Journal, Vol. 32, No. 8. pp. 1598-1605. https://doi.org/10.2514/3.12149
  17. Odgaard, A. J., and Kennedy, J. F. (1983). "River-bend bank protection by submerged vanes." Journal of Hydraulic Engineering, Vol. 109, No. 8, pp. 1161-1173. https://doi.org/10.1061/(ASCE)0733-9429(1983)109:8(1161)
  18. Odgaard, A. J., and Mosconi, C. E. (1987). "Streambank protection by submerged vanes." Journal of Hydraulic Engineering, Vol. 113, No. 4, pp. 520-536. https://doi.org/10.1061/(ASCE)0733-9429(1987)113:4(520)
  19. Odgaard, A. J., and Wang, Y. (1991a). "Sediment management with submerged vanes. I: Theory." Journal of Hydraulic Engineering, Vol. 117, No. 3, pp. 267-283. https://doi.org/10.1061/(ASCE)0733-9429(1991)117:3(267)
  20. Odgaard, A. J., and Wang, Y. (1991b). "Sediment management with submerged vanes. II: Applications." Journal of Hydraulic Engineering, Vol. 117, No. 3, pp. 284-302. https://doi.org/10.1061/(ASCE)0733-9429(1991)117:3(284)
  21. OpenFOAM (2018). OpenFOAM - The open source CFD toolbox 1812 User's Guide.
  22. Paik, J., Escauriaza, C., and Sotiropoulos, F. (2010). "Coherent structure dynamics in turbulent flows past in-stream structures: Some insights gained via numerical simulation." Journal of Hydraulic Engineering, Vol. 136, No. 12, pp. 981-993. https://doi.org/10.1061/(ASCE)HY.1943-7900.0000089
  23. Paik, J., Lee, N.-J., and Yoon, Y. H. (2017). "Numerical modeling of wave-type turbulent flow on a stepped weir." Journal of the Korean Society of Civil Engineers, KSCE, Vol. 37, No. 3, pp. 575-583. https://doi.org/10.12652/Ksce.2017.37.3.0575
  24. Park, S. D., Paik, J., Jeon, W. S., and Lee, H. J. (2019). "Super elevation and bed variation due to attack angle of submerged vanes in curved channel." Journal of the Korean Society of Civil Engineers, KSCE, Vol. 39, No. 2, pp. 297-306. https://doi.org/10.12652/KSCE.2019.39.2.0297
  25. Quyang, H.-T., Lai, J.-S., Yu, H., and Lu, C.-H. (2008). "Interaction between submerged vanes for sediment management." Journal of Hydraulic Research, Vol. 46, No. 5, pp. 620-727. https://doi.org/10.3826/jhr.2008.3160
  26. Rozovskii, I. L. (1957). Flow and water in bends of open channels. Academy of Sciences of the Ukrainian SSr, Isr. Progr. Sc. Transl., Jerusalem, Israel.
  27. Shur, M. L., Spalart, P. R., Stretlets, M. Kh., and Travin, A. K. (2008). "A hybrid RANS-LES approach with delatyed-DES and wall-modelled LES capabilities." International Journal of Heat and Fluid Flow, Vol. 29, No. 6, pp. 1638-1649. https://doi.org/10.1016/j.ijheatfluidflow.2008.07.001
  28. Sinha, S. K., and Marelius, F. (2000). "Analysis of flow past submerged vanes." Journal of Hydraulic Research, Vol. 38, No. 1, pp. 65-71. https://doi.org/10.1080/00221680009498360
  29. Thomson, W. (1876). "On the origin of windings of rivers in alluvial plains, with remarks on the flow of water round bends in pipes." Proceedings of Royal Society London, Vol. 25, pp. 5-8. https://doi.org/10.1098/rspl.1876.0004
  30. Voisin, A., and Townsend, R. D. (2002). "Model testing of submerged vane in strongly curved narrow channel bends." Canadian Journal of Civil Engineering, Vol. 29, No. 1, pp. 37-49. https://doi.org/10.1139/l01-078