Fluid Mechanics Calculator

Flow Rate

Q = V × A

Where A = πD²/4 for circular pipes. Common units: m³/s, L/s, gpm

Reynolds Number

Re = ρVD / μ

Re < 2300: Laminar
2300-4000: Transition
Re > 4000: Turbulent

Pressure Drop

ΔP = f × (L/D) × (ρV²/2)

Darcy-Weisbach equation for pipe friction losses

Bernoulli Equation

P/ρ + V²/2 + gz = constant

Conservation of energy for ideal fluids along a streamline

Typical Velocities

Water pipes: 1-3 m/s
Steam pipes: 15-30 m/s
Air ducts: 5-15 m/s

Common Fluids @ 20°C

Water: ρ=1000 kg/m³, μ=0.001 Pa·s
Air: ρ=1.2 kg/m³, μ=1.8×10⁻⁵ Pa·s