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Characterization of Flow Oblique to a Circular Cylinder with Low Aspect Ratio Using 3-D Detached Eddy Simulation

Published

Author(s)

Dong Hun Yeo, Nicholas P. Jones

Abstract

Large-amplitude vibrations of stay cables in cable-stayed bridges can threaten the safety and serviceability of the structures. Understanding of the excitation mechanism is necessary to mitigate such vibrations effectively and efficiently. Experimental research has investigated the mechanism of oscillation using flow oblique to a cylinder; however, since the aspect ratio of the cylinder is much lower than that of a real stay cable in bridges, the results might not reliably describe the real phenomenon. The current work applied three-dimensional detached eddy simulations (DES) to flow around a yawed and inclined cylinder to investigate the importance of the aspect ratio of a cylinder when flow oblique to the cylinder develops fully along its spanwise axis. Three aspect ratios of a cylinder (L/D = 10, 20, and 30; L: a cylinder length; D: a cylinder diameter) and two numerical conditions (slip and periodic) on spanwise boundaries were employed. Results showed that three-dimensional flow and the associated forces on a yawed and inclined cylinder are significantly influenced by the spanwise aspect ratios and spanwise boundary conditions. Even a 30D cylinder (i.e., a cylinder whose aspect ratio is 30) between slip spanwise walls did not fully capture characteristics of flow around a cylinder of infinite extent that were shown in simulations with periodic spanwise walls. This study suggests that when a wind tunnel experiment or a computational simulation investigates flow oblique to a very slender cylinder, such as attempting to model a stay cable, a sufficiently high spanwise aspect ratio of the cylinder must be used in order to accurately model inherently three-dimensional characteristics of the flow.
Citation
Journal of Wind Engineering and Industrial Aerodynamics

Keywords

cable vibration, cable-stayed bridge, yawed and inclined circular cylinder, detached eddy simulation, spanwise wall boundary condition, spanwise aspect ratio, end effect.

Citation

, D. and Jones, N. (2011), Characterization of Flow Oblique to a Circular Cylinder with Low Aspect Ratio Using 3-D Detached Eddy Simulation, Journal of Wind Engineering and Industrial Aerodynamics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=906122 (Accessed April 21, 2024)
Created January 31, 2011, Updated February 19, 2017