In fluid mechanics, the Roshko number (Ro) is a dimensionless number describing oscillating flow mechanisms. It is named after the Canadian Professor of Aeronautics Anatol Roshko. It is defined as
where St is the dimensionless Strouhal number; Re is the Reynolds number; U is mean stream velocity; f is the frequency of vortex shedding; L is the characteristic length (for example hydraulic diameter); ν is the kinematic viscosity of the fluid.
Correlations Roshko determined the correlationRoshko (1952) Figures 9 and 10 below from experiments on the flow of air around circular cylinders over range Re=50 to Re=2000:
valid over [ 50 <= Re < 200] valid over [200 <= Re < 2000]
Ormières and ProvansalOrmières and Provansal (1999), Figure 5 investigated vortex shedding in the wake of a sphere and found a relationship between Re and Ro in the range 280 < Re < 360.
Notes
References