Paul Richard Heinrich Blasius

Paul Richard Heinrich Blasius
Born	9 August 1883 Berlin, Brandenburg, Prussia, Imperial Germany
Died	24 April 1970(1970-04-24) (aged 86) Hamburg, West Germany
Citizenship	German
Nationality	German
Fields	Fluid mechanics and mechanical engineering
Alma mater	University of Göttingen
Doctoral advisor	Ludwig Prandtl
Known for	Blasius boundary layer

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 that is held parallel to a constant unidirectional flow \(U\).

Blasius' theorem

For a steady fluid flow with complex potential \(w(z)\) around a fixed body enclosed by a contour \(C\), the net force on the body due to fluid motion is given by

\[F_x - iF_y = \frac{i\rho}{2} \oint_{C} \left(\frac{dw}{dz}\right)^2 \, dz\]

where \(\rho\) is the constant fluid density. This is a contour integral which may be computed by using Cauchy's residue theorem.

Correlations

First law of Blasius for turbulent fanning friction factor:

\[f/2=0.039 Re^{-0.26} \, \]

Second law of Blasius for turbulent fanning friction factor:

\[f/2=0.023 Re^{-0.26} \, \]

Law of Blasius for friction coefficient in turbulent pipe flow:

\[\lambda=0.3164 Re^{-0.25} \, \]

See also

• Blasius function

References

• Hager, W.H., "Blasius: A life in research and education," Experiments in Fluids, 34: 566–571 (2003)
• Blasius, H., "Das Aehnlichkeitsgesetz bei Reibungsvorgängen in Flüssigkeiten", Mitteilungen über Forschungsarbeiten auf dem Gebiete des Ingenieurwesens, vol.131, VDI-Verlag Berlin (1913)

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