Thermal

Reynolds, Prandtl and Péclet Numbers

Enter values in the stated units. Example inputs are provided to help you explore the method.

Results

Your results will appear here after calculation. Changing an input clears the previous result.

Calculate dimensionless transport groups and diffusivities from fluid properties, a speed and a characteristic length. Defaults are an illustrative property set, not a certified fluid state.
Supply positive scalar properties for the same fluid and evaluation state. Dynamic viscosity μ is in Pa·s, not cP or m²/s; specific heat cp is in J/(kg·K), not kJ/(kg·K). This tool does not evaluate properties from temperature or pressure.
Kinematic viscosity ν = μ/ρ and thermal diffusivity α = k/(ρ cp), both in m²/s. Prandtl number Pr = ν/α = μ cp/k compares momentum and thermal diffusion.
Reynolds number Re = UL/ν. Choose the speed and length required by your intended model, such as bulk speed and inside diameter for a circular pipe. A plate length, hydraulic diameter and computational-cell size are different choices and are not automatically interchangeable.
Thermal Péclet number Pe = UL/α = Re × Pr when the same speed and length are used. It compares advection and thermal diffusion on those scales. This is not a mass-transfer Péclet number; that uses a mass diffusivity instead.
Zero speed gives Re = Pe = 0 while the material diffusivities and Pr remain defined. No universal laminar/turbulent classification, Nusselt correlation, heat-transfer coefficient or boundary-layer thickness is inferred. Match geometry, boundary conditions, property evaluation and validity range when selecting a correlation.