Reynolds number and its significance.

The Reynolds number (Re) is a dimensionless number used to predict fluid flow behavior. Re=ρvDμRe = \frac{\rho v D}{\mu}Re=μρvD​

Where:

• ρ = fluid density (kg/m³)
• v = velocity of fluid (m/s)
• D = characteristic dimension (e.g., pipe diameter in m)
• μ = viscosity of fluid (Pa·s)
• Re < 2000 → Laminar flow
• 2000 < Re < 4000 → Transition region
• Re > 4000 → Turbulent flow

Significance:

• Helps design pumps, reactors, and pipelines.
• Used in scale-up of chemical processes.
• Predicts heat & mass transfer coefficients.