For Stirling engines, the Schmidt number is related to the 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.
where:
*  is the Schmidt number
*  is the heat transferred into the working fluid
*  is the mean pressure of the working fluid
*  is the volume swept by the piston.