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 language | English (US) |
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State | Published - 2011 |
Event | 7th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2011 - Ottawa, Canada Duration: Jul 28 2011 → Jul 31 2011 |
Other
Other | 7th International Symposium on Turbulence and Shear Flow Phenomena, TSFP 2011 |
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Country/Territory | Canada |
City | Ottawa |
Period | 7/28/11 → 7/31/11 |
All Science Journal Classification (ASJC) codes
- Fluid Flow and Transfer Processes