Reynolds Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

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

Reynolds Number formula

\(\large{ Re = \frac{ \rho  v l_c }{ \mu }  }\)  

\(\large{ Re = \frac{ v l_c }{ \nu }  }\)

Where:

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

\(\large{ l_c }\) = characteristic length or diameter of the fluid flow

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

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

\(\large{ \mu }\)  (Greek symbol mu)  = dynamic viscosity

\(\large{ \nu }\)  (Greek symbol nu) = kinematic viscosity

Solve for:

\(\large{ l_c = \frac{ Re  \mu }{\rho v }  }\)

\(\large{ \rho = \frac{ Re  \mu }{ l_c v }  }\)

\(\large{ v = \frac{ Re  \mu }{ \rho l_c  }  }\)

\(\large{ \mu = \frac{ \rho v l_c }{ Re  }  }\)

 

Tags: Equations for Flow