In a turbulent channel-flow hot-film measurements have been made. To achieve a sublayer thickness of approximately 1 cm at y+ = 10, oil was used. The Reynolds numbers used for the investigations were 5,600 and 8,200 based on the channel-width of 22 cm and the channel center-line velocity.
In the vicinity of the wall, y+ < 0.1, the u'-fluctuations were found to be proportional to the wall distance, y+. The u'-values obtained with a hot-film probe for y+ > 0.7 were all greater than those obtained with a hot-film wall probe, but extrapolation of the data from the movable hot-film probe to the wall gave good agreement with the data from the flush-mounted wall-film probe.
The instantaneous values of the u'-fluctuations in the region 0 < y+ < 5 are very similar to the instantaneous values of the wall-gradient, but there is a time shift which is proportional to the wall distance, y+. Disturbances in the flow in this region were observed to be convected with a constant velocity toward the wall. The mean value of the convection velocity was found to be approximately equal to the friction velocity, uT.
The Reynolds stress was found to be intermittent in the vicinity of the wall with high peak to mean ratios.
It was found that the probability density of the instantaneous streamwise velocity is skewed for all y+ values except y+ ≈ 13. For y+ < 13 the most probable instantaneous velocity is less than the mean velocity; for y+ > 13 the opposite was found.
Eckelmann, H. and Reichardt, H., "An Experimental Investigation in a Turbulent Channel Flow With a Thick Viscous Sublayer (Hot-Film Measurements in Oil)" (1971). Symposia on Turbulence in Liquids. 86.
Symposium on Turbulence in Liquids (1971: Oct. 4-6, Rolla, MO)
Chemical and Biochemical Engineering
Article - Conference proceedings
Measurement and Analysis of Turbulence
© 1972 University of Missouri--Rolla, All rights reserved.