Kinematic Viscosity of Air Calculator
Calculate dynamic and kinematic viscosity of air at different temperatures and pressures
Calculate Air Viscosity
Air temperature for viscosity calculation
Absolute pressure of air
Air Properties
Dynamic Viscosity (μ)
Kinematic Viscosity (ν)
Formulas Used
Air Density: ρ = P/(R×T), where R = 287.05 J/(kg·K)
Dynamic Viscosity: μ = 1.458×10⁻⁶ × T³⁄² / (T + 110.4)
Kinematic Viscosity: ν = μ/ρ
Viscosity Analysis
Example Calculation
Standard Conditions
Temperature: 20°C (293.15 K)
Pressure: 1 atm (101,325 Pa)
Specific gas constant (R): 287.05 J/(kg·K)
Step-by-Step Calculation
1. Air density: ρ = 101,325 / (287.05 × 293.15) = 1.204 kg/m³
2. Dynamic viscosity: μ = 1.458×10⁻⁶ × 293.15³⁄² / (293.15 + 110.4) = 1.813×10⁻⁵ Pa·s
3. Kinematic viscosity: ν = 1.813×10⁻⁵ / 1.204 = 1.506×10⁻⁵ m²/s
Result: ν = 15.06 cSt or 0.1506 St
Viscosity Units
Dynamic Viscosity (μ)
• Pa·s (kg/m·s) - SI unit
• Poise (P) = 0.1 Pa·s
• centiPoise (cP) = 1 mPa·s
Kinematic Viscosity (ν)
• m²/s - SI unit
• Stokes (St) = 10⁻⁴ m²/s
• centiStokes (cSt) = 10⁻⁶ m²/s
• mm²/s = 1 cSt
Reference Values
At Sea Level (1 atm)
0°C: ν = 13.28 cSt
20°C: ν = 15.06 cSt
50°C: ν = 17.95 cSt
100°C: ν = 23.06 cSt
Comparison
Water (20°C): ~1.0 cSt
Air (20°C): ~15.1 cSt
Oil (20°C): ~50-500 cSt
Applications
Aerodynamics & aircraft design
Meteorology & weather modeling
HVAC system design
Fluid mechanics research
Understanding Air Viscosity
What is Viscosity?
Viscosity is a measure of a fluid's resistance to flow and deformation. For air, viscosity determines how much resistance there is to the motion of objects through the atmosphere and affects aerodynamic forces.
Dynamic vs Kinematic
- •Dynamic viscosity (μ): Absolute measure of fluid's resistance to shear
- •Kinematic viscosity (ν): Dynamic viscosity divided by density
- •Kinematic viscosity is more relevant for momentum transfer
Temperature Dependence
Unlike liquids, air viscosity increases with temperature. This is because higher temperatures increase molecular motion and intermolecular collisions.
Pressure Effects
Pressure has minimal effect on air viscosity but significantly affects density. Higher pressure increases density, which decreases kinematic viscosity.
Key Relationship: ν ∝ T³⁄² / P (at constant composition)
Sutherland's Formula
μ = μ₀ × (T/T₀)³⁄² × (T₀ + S)/(T + S)
Simplified form: μ = 1.458×10⁻⁶ × T³⁄² / (T + 110.4)
T₀: Reference temperature (273.15 K)
T: Absolute temperature (K)
Accuracy: ±2% for most conditions