Turbulent coherent structures in a thermally stable boundary layer

Owen Williams, Alexander J. Smits

Research output: Contribution to conferencePaper

1 Scopus citations

Abstract

The effects of thermal stability on coherent structures in turbulent flat plate boundary layers are examined experimentally. Thermocouple and DPIV measurements are reported over a Richardson number range 0 < Rid < 0.2. The reduction in wall shear and the damping of the turbulent stresses with increasing stability are qualitatively similar to that found by Ohya et al. (1996) including the major changes observed when the flow enters the strongly stable regime. In contrast, a critical bulk Richardson number of 0.05 is observed,which is much lower than the value of 0.25 found in this earlier study. In the weakly stable regime, hairpin vortices are seen to continue to populate the near-wall region and are elongated in the streamwise direction creating a smaller angle of inclination to the wall. With increasing stability, the angle of these structures continues to decrease and they are confined closer to the wall. In our experiments, the strongly stable flows show no evidence of large scale structures, or the presence of gravity waves.

Original languageEnglish (US)
StatePublished - Jan 1 2011
Event7th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2011 - Ottawa, Canada
Duration: Jul 28 2011Jul 31 2011

Other

Other7th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2011
CountryCanada
CityOttawa
Period7/28/117/31/11

All Science Journal Classification (ASJC) codes

  • Fluid Flow and Transfer Processes

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    Williams, O., & Smits, A. J. (2011). Turbulent coherent structures in a thermally stable boundary layer. Paper presented at 7th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2011, Ottawa, Canada.