A dimensionless quantity named after Osbourne Reynolds who first made know the difference between laminar and turbulent flow. The practical value of the Reynolds Number is that it indicated the degree of turbulence in a flowing liquid. It depends on the hydraulic radius of the conduit, the viscosity of the water and the velocity of flow. For a conduit of a given size, the velocity is generally the major variable and the Reynolds Number will increase as the velocity of flow increases.
Reynolds number ( Re) is a dimensionless quantity used in fluid mechanics, defined by Re = vl/ where is density, is velocity, is length, and is viscosity.
A dimensionless number that characterizes fluid flow through a system. At low Reynolds number, a fluid viscosity dominates the flow while at high Reynolds numbers, a fluid's inertia dominates.