Schmidt number

Schmidt number is a dimensionless number defined as the ratio of momentum diffusivity (viscosity) and mass diffusivity, and is used to characterize fluid flows in which there are simultaneous momentum and mass diffusion convection processes. It was named after the German engineer Ernst Heinrich Wilhelm Schmidt (1892-1975).

Schmidt number is the ratio of the shear component for diffusivity "viscosity/density" to the diffusivity for mass transfer "D". It physically relates the relative thickness of the hydrodynamic layer and mass-transfer boundary layer.

It is defined [Citation
last1 = Incropera | first1 = Frank P.
last2 = DeWitt | first2 = David P.
title = Fundamentals of Heat and Mass Transfer
edition = 3rd Ed.
publisher = John Wiley & Sons
year = 1990
pages = p. 345
isbn = 0-471-51729-1 Eq. 6.71.] as::$mathit\{Sc\}\; =\; frac\{\; u\}\{D\}\; =\; frac\; \{mu\}\; \{\; ho\; D\}$

where:
* $u$ is the kinematic viscosity
* $D$ is the mass diffusivity.
* $mu$ is the Viscosity
* $ho$ is the DensityThe heat transfer analog of the Schmidt number is the Prandtl number.

tirling engines

For Stirling engines, the Schmidt number represents dimensionless specific power.
Gustav Schmidt of the German Polytechnic Institute of Prague published an analysis in 1871 for the now-famous closed-form solution for an idealized isothermal Stirling engine model. [ [http://www.ent.ohiou.edu/~urieli/stirling/isothermal/Schmidt.html Schmidt Analysis (updated 12/05/07) ] ] [http://mac6.ma.psu.edu/stirling/simulations/isothermal/schmidt.html]

:

where,
* $Sc$ is the Schmidt number
* $Q$ is the heat transferred into the working fluid
* is the mean pressure of the working fluid
* $V\_\{sw\}$ is the volume swept by the piston

ee also

Notes