Physics
Viscosity/Fluid Dynamics
Reynolds Number
11
⚡ Quick Summary
Reynolds number (Re) is a dimensionless quantity that helps predict flow patterns in fluids. A low Re indicates laminar (steady) flow, while a high Re indicates turbulent flow.
Re = (ρvd)/η
The Reynolds number is defined as: Re = (ρvd)/η where: ρ is the density of the fluid, v is the flow speed, d is the characteristic length (e.g., diameter of a tube), and η is the dynamic viscosity of the fluid. A flow is generally considered steady or laminar if the Reynolds number is below a critical value (typically around 2000 for flow in a pipe). Above this value, the flow becomes turbulent.