Prandtl Number Calculator
Pr relates momentum and thermal diffusivities: Pr = ν/α = cp μ / k.
How to Use This Calculator
1
Gather properties
Use cp, μ, and k for your fluid at the operating temperature.
2
Enter values
Ensure consistent SI units.
3
Calculate Pr
Interpret convective behavior based on Pr.
Formula
Pr = cp · μ / k
Where: cp is specific heat, μ dynamic viscosity, k thermal conductivity.
Example (air): cp=1005 J/kg·K, μ=1.8e-5 Pa·s, k=0.026 W/m·K ⇒ Pr≈0.696.
Frequently Asked Questions
Typical values?
Air ~0.7, water ~7 at room temperature; oils can be much greater than 100.
Temperature dependence?
All three properties vary with temperature; use values at film temperature for convection.