Question

strouhal number definition

Answer 1

In dimensional analysis, the Strouhal number (St) is a dimensionless number describing oscillating flow mechanisms. The parameter is named after Vincenc Strouhal, a Czech physicist who experimented in 1878 with wires experiencing vortex shedding and singing in the wind.[1][2] The Strouhal number is an integral part of the fundamentals of fluid mechanics.

The Strouhal number is often given as;

{\displaystyle \mathrm {St} ={fL \over U},}

where f is the frequency of vortex shedding, L is the characteristic length (for example hydraulic diameter, or the airfoil thickness) and U is the flow velocity. In certain cases like heaving (plunging) flight, this characteristic length is the amplitude of oscillation. This selection of characteristic length can be used to present a distinction between Strouhal number and Reduced Frequency.

{\displaystyle \mathrm {St} ={ka \over \pi c},}