Scruton number

The Scruton number Sc is an important parameter for vortex-induced vibration (excitation) of structures, vibrations caused by rain or wind, dry inclined cable galloping, and wake galloping, the unstable airflow that forms around bridge cables and other cylindrically-structured buildings.[1] It is named after Christopher "Kit" Scruton, a British industrial dynamics engineer.[2][3]

It is defined by:[4]

${\displaystyle Sc={\frac {2\delta _{s}m_{e}}{\rho b_{\text{ref}}^{2}}},}$

where

${\displaystyle \delta _{s}}$	is the structural damping expressed by the logarithmic damping decrement,
${\displaystyle m_{e}}$	is the effective mass per unit length,
${\displaystyle \rho }$	is the density of the air, or liquid,
${\displaystyle b_{\text{ref}}}$	is the characteristic width of the structure.

References

1. "MECHANICS OF WIND-INDUCED VIBRATIONS". Federal Highway Administration Research and Technology. August 2007. Retrieved 17 January 2017.
2. Wenzel, Helmut (2008). Health Monitoring of Bridges. Wiley. p. 464. ISBN 978-0-470-74018-7.
3. Ted Stathopoulos; Charalambos C. Baniotopoulos (31 December 2007). Wind Effects on Buildings and Design of Wind-Sensitive Structures. Springer Science & Business Media. p. 45. ISBN 978-3-211-73076-8.
4. "Vortex-induced vibrations of structures" (PDF). 1991. Retrieved 17 January 2017.