Changes in profile shape were shown to correlate with the local stratification profile, and as a result, the collapse of near-wall turbulence is not intrinsic to the strongly stable regime. The turbulent stresses were found to scale with the wall shear stress in the weakly stable regime prior relaminarization at a critical stratification. To examine the characteristics of these two regimes, PIV measurements were ob- tained in conjunction with the mean temperature profile in a low Reynolds number facility over smooth and rough surfaces. Previous experimental studies examining the e↵ects of stability on turbulent boundary layers identified two regimes, weak and strong stability, separated by a critical bulk stratifi- cation with a collapse of near-wall turbulence thought to be intrinsic to the strongly stable regime. Two distinct cases were examined: the thermally stable atmospheric surface layer characteristic of nocturnal or po- lar conditions, and the hypersonic bounder layer characteristic of high speed aircraft and reentering spacecraft.
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