In fluid mechanics, the Roshko number (Ro) is a dimensionless number describing oscillating flow mechanisms. It is named after the American Professor of Aeronautics Anatol Roshko. It is defined as
where
Roshko determined the correlation[1] below from experiments on the flow of air around circular cylinders over range Re=50 to Re=2000:
Ormières and Provansal[2] investigated vortex shedding in the wake of a sphere and found a relationship between Re and Ro in the range 280 < Re < 360.