Roshko number

In fluid mechanics, the Roshko number is a dimensionless number describing oscillating flow mechanisms. It is given as:


 * $$ \mathit{Ro} = {St} {Re} = {f L^{2}\over \nu} $$

where Ro is the dimensionless Roshko number, St is the dimensionless Strouhal number, Re is the Reynolds number, f is the frequency of vortex shedding, L is the characteristic length (for example hydraulic diameter) and ν is the kinematic viscosity of the fluid.