The Reynolds number for a pipe or duct expressed in Imperial units The Reynolds Number for the flow in a duct or pipe can with the hydraulic diameter be expressed asĭ h = hydraulic diameter (m, ft) Reynolds Number for a Pipe or Duct in Imperial Units Ν = μ / ρ = kinematic viscosity (m 2 /s, ft 2 /s) Reynolds Number for Flow in Pipe or Ductįor a pipe or duct the characteristic length is the hydraulic diameter. Μ = dynamic viscosity (Ns/m 2, lb m /s ft) U = velocity based on the actual cross section area of the duct or pipe (m/s, ft/s) Reynolds Number can therefore be expressed as
dynamic pressure (ρ u 2 ) to shearing stress (μ u / L).inertia force (ρ u L) to viscous or friction force (μ).Reynolds Number - the non-dimensional velocity - can be defined as the ratio
