text: 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 
  * 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.