Paul Richard Heinrich Blasius

Paul Richard Heinrich Blasius (1883 - 1970) was a German fluid dynamics engineer.

He was one of the first students of Prandtl who provided a mathematical basis for boundary-layer drag but also showed as early as 1911 that the resistance to flow through smooth pipes could be expressed in terms of the Reynolds number for both laminar and turbulent flow.

One of his most notable contributions involves a description of the steady two-dimensional boundary-layer that forms on a semi-infinite plate which is held parallel to a constant unidirectional flow $$U$$.

Correlations
First law of Blasius for Turbulent fanning friction factor:

$$f/2=0.039*Re^-0.25$$

Second law of Blasius for Turbulent fanning friction factor:

$$f/2=0.023*Re^-0.2$$