Prandtl Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Prandtl number, abbreviated as Pr, is a dimensionless number used in fluid dynamics is used to calculate force by the ratio of momentum diffusivity (kinematic viscosity) and thermal diffusivities.  This number helps characterize the relative thickness of the velocity boundary layer to the thermal boundary layer.  The calculation and equations for determining the Prandtl number is shown below.

\(\large{ Pr= \frac{\nu} {\alpha}  }\)         


\(\large{ Pr }\) = Prandtl number

\(\large{ \nu }\)  (Greek symbol nu) = kinematic viscosity

\(\large{ \alpha }\)  (Greek symbol alpha) = thermal diffusivity

Solve for:

\(\large{ \nu =  Pr  \;  \alpha  }\)

\(\large{ \alpha = \frac { \nu  }{  Pr  }    }\)

Note: Unit conversion is done automatically and is built into the calculation.


Tags: Equations for Force