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] where