On the parameter β=Re/KC=D2/νT

This brief communication is a summary of the facts regarding the universalization in 1976 of a parameter β to fully nonlinear unsteady separated flows about bluff bodies nearly 125 years after its first appearance in a linearized analysis of unseparated viscous flow with very slow oscillations about a cylindrical rod and sphere by Sir George Gabriel Stokes [1851. On the effect of the internal friction of fluids on the motion of pendulums. Transactions of the Cambridge Philosophical Society 9(II), 8-106]. The primary purpose of Stokes was to show that “the index of friction” (the kinematic viscosity), in the equations of motion may be deduced from experiments for the vindication of the heuristic reasoning that went into the derivation by Navier [1827. Mémoire sur les lois du movement des fluides. Mémoires de l'Académie de Sciences 6, 389-416.], Poisson [1831. Nouvelle théorie de l'action capillaire Bachelier, Paris.], de Saint-Venant [1843. Note á joindre un memoire sur la dynamique des fluides. Comptes Rendus 17, 1240-1244.] and Stokes [1845. On the theories of internal friction of fluids in motion. Transactins of the Cambridge Philosophical Society 8, 287-305.] of what are now called the Navier-Stokes equations.