Strouhal number

In dimensional analysis, the Strouhal number is a quantity describing oscillating flow mechanisms. Often, it is given as

<math> Sr= {f D\over V} <math>

where Sr is the Strouhal number, f is the frequency of vortex shedding, D is the hydraulic diameter of the object in the fluid flow and V is the velocity of the fluid. The Strouhal number is a function of the Reynolds number Re and in the region 200<Re<200,000 it is assumed to be equal to 0.2.

See also: dimensionless number (which includes a listing of other dimensionless numbers)