Method and variables
Property form: Pr = μCp/k. Diffusivity form: Pr = ν/α.
- μ — dynamic viscosity
- Cp — specific heat capacity at constant pressure
- k — fluid thermal conductivity
- ν — kinematic viscosity
- α — thermal diffusivity
Worked example
For water near 20 °C, μ = 1.002 mPa·s, Cp = 4182 J/(kg·K), and k = 0.598 W/(m·K). The result is Pr ≈ 7.01.
How it connects to other tools
Prandtl number is usually paired with Reynolds number in forced-convection correlations, or Rayleigh number in natural-convection correlations. It is an input to a correlation, not a complete heat-transfer design result.
Important limits
Properties vary with temperature, pressure and composition. Enter all values at the same reference state. This calculator does not choose a correlation, validate its range or calculate a heat-transfer coefficient.
References
Related tools
Reynolds Number Calculator · Heat Conduction Calculator · Dimensionless Numbers Calculators
Frequently asked questions
What does the Prandtl number represent?
It is the ratio of momentum diffusivity to thermal diffusivity. It helps compare the relative development of velocity and thermal boundary layers in a fluid.
How is Prandtl number calculated?
Use Pr = μCp/k when dynamic viscosity, specific heat and thermal conductivity are known. The equivalent form is Pr = ν/α.
Does Prandtl number calculate heat transfer coefficient?
No. It is an input to many convection correlations. A heat-transfer coefficient additionally depends on geometry, flow conditions and an applicable correlation.