Experimental reconsideration of spatio-temporal dynamics observed in fluid-elastic oscillator arrays from complex system viewpoint: From vibrating pipes in heat exchangers to waving plants in agricultural fields
✍ Scribed by Masaharu Kuroda; Francis C. Moon
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 733 KB
- Volume
- 12
- Category
- Article
- ISSN
- 1076-2787
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✦ Synopsis
Abstract
Transition from local complexity to global spatio‐temporal dynamics in a two‐dimensional array of fluid‐elastic oscillators is examined experimentally with an apparatus comprising 90‐1000 cantilevered rods in a wind tunnel as the Reynolds number (based on rod diameter) is increased from 200 to 900. A cluster‐pattern entropy measure is introduced as a quantitative measure of local complexity. As the intensity of interaction among neighboring elements (in this case, frequency of collisions among rods) increases, a set of the elements (in this case, a rod‐array) achieves globally better‐organized behavior. On the basis of accelerometer data, the rod impact rate versus flow velocity shows a power‐law scaling relation. Video images reveal that, initially, each rod moves individually; then clusters consisting of several rods emerge. Finally, global wave‐like motion occurs at higher flow velocities. Each wave‐like motion has its specific frequency and spatial wavelength, which vary according to wind velocity. © 2007 Wiley Periodicals, Inc. Complexity 12: 36–47, 2007