| Paul Richard Heinrich Blasius | |
| Birth Date: | 9 August 1883 |
| Birth Place: | Berlin, Brandenburg, Prussia, Imperial Germany |
| Death Place: | Hamburg, West Germany |
| Citizenship: | German |
| Nationality: | German |
| Field: | Fluid mechanics and mechanical engineering |
| Alma Mater: | University of Göttingen |
| Thesis Title: | Boundary layers in liquids with low friction |
| Thesis Year: | 1907 |
| Doctoral Advisor: | Ludwig Prandtl |
| Known For: | Blasius boundary layer Blasius theorem |
Paul Richard Heinrich Blasius (9 August 1883 – 24 April 1970) was a German fluid dynamics physicist. He was one of the first students of Prandtl.
Blasius 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. After six years in science he changed to Ingenieurschule Hamburg (today: University of Applied Sciences Hamburg) and became a Professor. On 1 April 1962 Heinrich Blasius celebrated his 50th anniversary in teaching. He was active in his field until he died on 24 April 1970.
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
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First law of Blasius for turbulent Fanning friction factor:
f/2=0.039Re-0.25
Second law of Blasius for turbulent Fanning friction factor:
f/2=0.023Re-0.22
Law of Blasius for friction coefficient in turbulent pipe flow:
λ=0.3164Re-0.25