Reynolds Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Reynolds number ( \(Re\) ) (dimensionless number) is the ratio of inertial forces (forces that remain at rest or in uniform motion) to viscosity forces (the resistance to flow).      

Reynolds Number formula

\(\large{ Re = \frac{ \rho  v l }{ \eta }  }\)         


\(\large{ Re }\) = Reynolds number

\(\large{ l_c }\) = Characteristic Length (diameter of the fluid flow)

\(\large{ \rho }\)  (Greek symbol rho) = density of the fluid

\(\large{ v }\) = velocity of the fluid

\(\large{ \eta }\)  (Greek symbol eta)  = viscosity of the fluid


Tags: Equations for Flow