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. It is named after Christopher "Kit" Scruton, a British industrial dynamics engineer.

It is defined by:


 * $$Sc = \frac{2\delta_sm_e}{\rho b^2_\text{ref}},$$

where


 * $$\delta_s$$ || is the structural damping expressed by the logarithmic damping decrement,
 * $$m_e$$ || is the effective mass per unit length,
 * $$\rho$$ || is the density of the air, or liquid,
 * $$b_\text{ref}$$ || is the characteristic width of the structure.
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 * $$\rho$$ || is the density of the air, or liquid,
 * $$b_\text{ref}$$ || is the characteristic width of the structure.
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