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ID 119361
Author
Nakamura, Ikuo Nagoya University
Keywords
Boundary layer
Turbulence
Structure function
Spatial correlation
Spatiotemporal structure
Two-point velocity difference
Content Type
Journal Article
Description
The streamwise velocity at two points in a turbulent boundary layer under zero pressure gradient was measured using two hot-wire probes separated in the wall-normal direction. The time trace of the fluctuating velocity difference, probability density function, fluctuating vorticity, structure function, and the spatial correlation coefficient was obtained. First, the physical importance of structure functions was explained in some detail. Then, the results of the measurements were considered. When the spatial separation between two points is small, the fluctuating velocity difference decreases monotonically as the two points move away from the wall. On the other hand, as the spatial separation increases, the similarity between the two fluctuating velocities decreases. In addition, the fluctuating velocity at the nearer point from the wall becomes dominant. When moving away from the wall, the fluctuating velocity difference first increases, then reaches a maximum, and finally decreases. When both positions are within the logarithmic region or defect region, the velocity difference is made between similar fluctuating velocities. Hence, the probability density function distribution shape is symmetrical with respect to positive and negative values, close to the Gaussian distribution. The fluctuating vorticity decreases monotonically as it moves away from the wall, regardless of the spatial separation. The structure function increases as the separation increases. Away from the wall, the length over which the correlation is maintained increases, resulting in a large eddy.
Journal Title
Journal of Fluid Science and Technology
ISSN
18805558
Publisher
日本機械学会
Volume
19
Issue
3
Start Page
JFST0028
Published Date
2024
Rights
This is an open access article under the terms of the Creative Commons Attribution 4.0 International license (https://creativecommons.org/licenses/by/4.0/).
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DOI (Published Version)
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language
eng
TextVersion
Publisher
departments
Science and Technology