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Proceedings Paper

Sensor for direct measurement of the boundary shear stress in fluid flow
Author(s): Xiaoqi Bao; Mircea Badescu; Yoseph Bar-Cohen; Shyh-Shiuh Lih; Stewart Sherrit; Zensheu Chang; Beck Chen; Scott Widholm; Patrick Ostlund
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Paper Abstract

The formation of scour patterns at bridge piers is driven by the forces at the boundary of the water flow. In most experimental scour studies, indirect processes have been applied to estimate the shear and normal stress using measured velocity profiles. The estimations are based on theoretical models and associated assumptions. However, the turbulence flow fields and boundary layer in the pier-scour region are very complex. In addition, available turbulence models cannot account accurately for the bed roughness effect. Direct measurement of the boundary shear and normal stress and their fluctuations are attractive alternatives. However, this approach is a challenging one especially for high spatial resolution and high fidelity measurements. The authors designed and fabricated a prototype miniature shear stress sensor including an EDM machined floating plate and a high-resolution optical encoder. Tests were performed both in air as well as operation in water with controlled flow. The sensor sensitivity, stability and signal-to-noise level were measured and evaluated. The detailed test results and a discussion of future work will be presented in this paper.

Paper Details

Date Published: 16 April 2011
PDF: 8 pages
Proc. SPIE 7981, Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2011, 79814G (16 April 2011); doi: 10.1117/12.880901
Show Author Affiliations
Xiaoqi Bao, Jet Propulsion Lab. (United States)
Mircea Badescu, Jet Propulsion Lab. (United States)
Yoseph Bar-Cohen, Jet Propulsion Lab. (United States)
Shyh-Shiuh Lih, Jet Propulsion Lab. (United States)
Stewart Sherrit, Jet Propulsion Lab. (United States)
Zensheu Chang, Jet Propulsion Lab. (United States)
Beck Chen, Jet Propulsion Lab. (United States)
Scott Widholm, Jet Propulsion Lab. (United States)
Patrick Ostlund, Jet Propulsion Lab. (United States)


Published in SPIE Proceedings Vol. 7981:
Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2011
Masayoshi Tomizuka, Editor(s)

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