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Korean Meteorological Society (한국기상학회)
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Analysis on Vortex Streets Behind a Square Cylinder at High Reynolds Number Using a Large-Eddy Simulation Model: Effects of Wind Direction, Speed, and Cylinder Width

큰에디모의 모형을 이용한 높은 레이놀즈 수에서의 사각 기둥 후면의 와열 분석: 풍향과 풍속, 기둥 너비의 영향

  • Han, Beom-Soon (School of Earth and Environmental Sciences, Seoul National University) ;
  • Kwak, Kyung-Hwan (School of Natural Resources and Environmental Science, Kangwon National University) ;
  • Baik, Jong-Jin (School of Earth and Environmental Sciences, Seoul National University)
  • 한범순 (서울대학교 지구환경과학부) ;
  • 곽경환 (강원대학교 환경융합학부) ;
  • 백종진 (서울대학교 지구환경과학부)
  • Received : 2017.08.31
  • Accepted : 2017.12.04
  • Published : 2017.12.31
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Abstract

This study investigates turbulent flow around a square cylinder mounted on a flat surface at high Reynolds number using a large-eddy simulation (LES) model, particularly focusing on vortex streets behind the square cylinder. Total 9 simulation cases with different inflow wind directions, inflow wind speeds, and cylinder widths in the x- and y-directions are considered to examine the effects of inflow wind direction, speed, and cylinder widths on turbulent flow and vortex streets. In the control case, the inflow wind parallel to the x-direction has a maximum speed of $5m\;s^{-1}$ and the width and height of the cylinder are 50 m and 200 m, respectively. In all cases, down-drafts in front of the cylinder and updrafts, wakes, and vortex streets behind the cylinder appear. Low-speed flow below the cylinder height and high-speed flow above it are mixed behind the cylinder, resulting in strong negative vertical turbulent momentum flux at the boundary. Accordingly, the magnitude of the vertical turbulent momentum flux is the largest near the cylinder top. In the case of an inflow wind direction of $45^{\circ}$, the height of the boundary is lower than in other cases. As the inflow wind speed increases, the magnitude of the peak in the vertical profile of mean turbulent momentum flux increases due to the increase in speed difference between the low-speed and high-speed flows. As the cylinder width in the y-direction increases, the height of the boundary increases due to the enhanced updrafts near the top of the cylinder. In addition, the magnitude of the peak of the mean turbulent momentum flux increases because the low-speed flow region expands. Spectral analysis shows that the non-dimensional vortex generation frequency in the control case is 0.2 and that the cylinder width in the y-direction and the inflow wind direction affect the non-dimensional vortex generation frequency. The non-dimensional vortex generation frequency increases as the projected width of the cylinder normal to the inflow direction increases.

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References

  1. Bourgeois, J. A., P. Sattari, and R. J. Martinuzzi, 2011: Alternating half-loop shedding in the turbulent wake of a finite surface-mounted square cylinder with a thin boundary layer. Phys. Fluids, 23, 095101, doi:10.1063/1.3623463.
  2. Breuer, M., 1998: Large eddy simulation of the subcritical flow past a circular cylinder: Numerical and modeling aspects. Int. J. Numer. Meth. Fl., 28, 1281-1302. https://doi.org/10.1002/(SICI)1097-0363(19981215)28:9<1281::AID-FLD759>3.0.CO;2-#
  3. Deardorff, J. W., 1980: Stratocumulus-capped mixed layers derived from a three-dimensional model. Bound.-Layer Meteor., 18, 495-527. https://doi.org/10.1007/BF00119502
  4. Han, B.-S., S.-B. Park, J.-J. Baik, J. Park, and K.-H. Kwak, 2017: Large-eddy simulation of vortex streets and pollutant dispersion behind high-rise buildings. Quart. J. Roy. Meteor. Soc., 143, 2714-2726, doi:10.1002/qj.3120.
  5. Islam, S. U., C. Y. Zhou, A. Shah, and P. Xie, 2012: Numerical simulation of flow past rectangular cylinders with different aspect ratios using the incompressible lattice Boltzmann method. J. Mech. Sci. Tech., 26, 1027-1041, doi:10.1007/s12206-012-0328-4.
  6. Krajnovic, S., 2011: Flow around a tall finite cylinder explored by large eddy simulation. J. Fluid Mech., 676, 294-317, doi:10.1017/S0022112011000450.
  7. Lienhard, J. H., 1966: Synopsis of Lift, Drag, and Vortex Frequency Data for Rigid Circular Cylinders. Technical Extension Service, 32 pp.
  8. Maronga, B., and Coauthors, 2015: The Parallelized Large-Eddy Simulation Model (PALM) version 4.0 for atmospheric and oceanic flows: Model formulation, recent developments, and future perspectives. Geosci. Model Dev., 8, 1539-1637, doi:10.5194/gmdd-8-1539-2015.
  9. Norberg, C., 2003: Fluctuating lift on a circular cylinder: Review and new measurements. J. Fluids Struct., 17, 57-96. https://doi.org/10.1016/S0889-9746(02)00099-3
  10. Palau-Salvador, G., T. Stoesser, J. Frohlich, M. Kappler, and W. Rodi, 2010: Large eddy simulations and experiments of flow around finite-height cylinders. Flow Turbul. Combust., 84, 239-275, doi:10.1007/s10494-009-9232-0.
  11. Sattari, P., J. A. Bourgeois, and R. J. Martinuzzi, 2012: On the vortex dynamics in the wake of a finite surfacemounted square cylinder. Exp. Fluids, 52, 1149-1167, doi:10.1007/s00348-011-1244-6.
  12. Sohankar, A., C. Norbergb, and L. Davidson, 1997: Numerical simulation of unsteady low-Reynolds number flow around rectangular cylinders at incidence. J. Wind Eng. Ind. Aerod., 69, 189-201.
  13. Sumner, D., J. L. Heseltine, and O. J. P. Dansereau, 2004: Wake structure of a finite circular cylinder of small aspect ratio. Exp. Fluids, 37, 720-730. https://doi.org/10.1007/s00348-004-0862-7
  14. Sumner, D., 2013: Flow above the free end of a surfacemounted finite-height circular cylinder: A review. J. Fluid Struct., 43, 41-63, doi:10.1016/j.jfluidstructs.2013.08.007.
  15. Uffinger, T., I. Ali, and S. Becker, 2013: Experimental and numerical investigations of the flow around three different wall-mounted cylinder geometries of finite length. J. Wind Eng. Ind. Aerod., 119, 13-27, doi:10.1016/j.jweia.2013.05.006.
  16. Wang, H. F., Y. Zhou, C. K. Chan, W. O. Wong, and K. S. Lam, 2004: Flow structure around a finite-length square prism. Proc. of the 15th Australasian Fluid Mechanics Conference, Sydney, Australia. [Available online at https://www.researchgate.net/profile/Ck_Chan2/publication/237307611_Flow_Structure_Around_A_Finite-Length_Square_Prism/links/551958470cf2d241f3563737.pdf.]
  17. Wang, H. F., and Y. Zhou, 2009: The finite-length square cylinder near wake. J. Fluid Mech., 638, 453-490. https://doi.org/10.1017/S0022112009990693
  18. Wicker, L. J., and W. C. Skamarock, 2002: Time-splitting methods for elastic models using forward time schemes. Mon. Wea. Rev., 130, 2088-2097. https://doi.org/10.1175/1520-0493(2002)130<2088:TSMFEM>2.0.CO;2