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Transition of Turbulent Boundary Layer with a Step Change from Smooth to Rough Surface

표면 형상 변화에 따른 난류경계층 유동장 분석

  • Received : 2014.12.09
  • Accepted : 2014.12.18
  • Published : 2014.12.31

Abstract

Direct numerical simulation (DNS) dataset of a turbulent boundary layer (TBL) with a step change from smooth to rough surface is analyzed to examine spatially developing flow characteristics. The roughness elements are periodically arranged two-dimensional (2-D) spanwise rods with a streamwise pitch of ${\lambda}=8k$ ($=12{\theta}_{in}$), and the roughness height is $k=15{\theta}_{in}$, where ${\theta}_{in}$ is the inlet momentum thickness. The step change is introduced $80{\theta}_{in}$ downstream from the inlet. For the first time, full images from the DNS data with the step change from the smooth to rough walls is present to get some idea of the geometry of turbulent coherent structures over rough wall, especially focusing on their existence and partial dynamics over the rough wall. The results show predominance of hairpin vortices over the rough wall and their spanwise scale growth mechanism by merging.

Acknowledgement

Supported by : 한국연구재단

References

  1. Jackson, P.S., 1976, "The propagation of modified flow downstream of a change in roughness," Quart. J. Roy. Meteorol. Soc., Vol. 102, pp.924-933.
  2. Bradley, E.F., 1968, "A micrometeorological study of velocity profile and surface drag in the region modified by a change in surface roughness," Quart. J. Roy. Meteorol. Soc., Vol. 94, pp.361-379. https://doi.org/10.1002/qj.49709440111
  3. Pendergrass, W., Arya, S.P.S., 1984, "Dispersion in neutral boundary layer over a step change in surface roughness - I. Mean flow and turbulence structure," Atmos. Environ., Vol.18, pp.1267-1279. https://doi.org/10.1016/0004-6981(84)90037-4
  4. Andreopoulos, J., Wood, D.H., 1982, "The response of a turbulent boundary layer to a short length of surface roughness," J. Fluid Mech., Vol.118, pp.143-164. https://doi.org/10.1017/S0022112082001001
  5. Cheng, H., Castro, I.P., 2002, "Near-wall flow development after a step change in surface roughness," Boundary layer Met., Vol.104, pp.229-259. https://doi.org/10.1023/A:1016060103448
  6. Antonia, R.A., Luxton, R.E., 1971, "The response of a turbulent boundary layer to a step change in surface roughness," J. Fluid Mech., Vol.48, pp.721-761. https://doi.org/10.1017/S0022112071001824
  7. Lee, J.H., Seena, A., Lee, S.-H., Sung, H.J., 2012, "Turbulent boundary layers over rod- and cuberoughened walls," J. Turbul., Vol.13, pp.1-26. https://doi.org/10.1080/14685248.2011.633522
  8. Marusic, I., 2009, "Unravelling turbulence near walls," J. Fluid Mech., Vol.630, pp.1-4. https://doi.org/10.1017/S0022112009007708
  9. Wu, X., Moin, P., 2010, "Transitional and turbulent boundary layer with heat transfer," Phys. Fluids, Vol.22, 085105. https://doi.org/10.1063/1.3475816
  10. Jimenez, J., Hoyas, S., Simens, M.P., Mizuno, Y., 2010, "Turbulent boundary layers and channels at moderate Reynolds numbers," J. Fluid Mech., Vol. 657, pp.335-360. https://doi.org/10.1017/S0022112010001370
  11. Schlatter, P., Orlu, R., 2012, "Turbulent boundary layers at moderate Reynolds numbers: inflow length and tripping effects," J. Fluid Mech., Vol.710, pp.5-34. https://doi.org/10.1017/jfm.2012.324
  12. Adrian, R.J., 2007, "Hairpin vortex organization in wall turbulence," Phys. Fluids, Vol.19, 041301. https://doi.org/10.1063/1.2717527
  13. Kim, K., Baek, S.-J., Sung, H.J., 2002, "An implicit velocity decoupling procedure for the incompressible Navier-Stokes equations," Int. J. Numer. Meth. Fluids, Vol.38, pp.125-138. https://doi.org/10.1002/fld.205
  14. Kim, J., Kim. D., Choi, H., 2001, "An immersed boundary infinite-volume method for simulations of flow in complex geometries," J. Comput. Phys., Vol.171, pp.132-150. https://doi.org/10.1006/jcph.2001.6778
  15. Lund, T.S., Wu, X., Squires, K.D., 1998, "Generation of turbulent inflow data for spatially-developinig boundary layer simulatioin," J. Comput. Phys., Vol.140, pp.233-258. https://doi.org/10.1006/jcph.1998.5882
  16. Lee, S.-H., Sung, H.J., 2007, "Direct numerical simulation of the turbulent boundary layer over a rod-roughened wall," J. Fluid Mech., Vol.584, pp. 125-146. https://doi.org/10.1017/S0022112007006465
  17. Theodorsen, T., 1952, "Mechanism of turbulence," In Proc. Second Midwestern Conference on Fluid Mechanics, Mar. 17-19. Ohio State Univ., Columbus, OH, USA.
  18. Zhou, J., Adrian, R.J., Balachandar, S., Kendall, T.M., 1999, "Mechanisms for generating coherent packets of hairpin vortices," J. Fluid Mech., Vol.387, pp.353-396. https://doi.org/10.1017/S002211209900467X