Oskar Tietjens

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Oskar Karl Gustav Tietjens (born April 23, 1893 in Wandsbeck , † October 23, 1971 in Freiburg im Breisgau ) was a German fluid mechanic.

Life

Tietjens studied shipbuilding at the TH Berlin-Charlottenburg from 1912 , which was interrupted by military service in the First World War. After the war he continued his studies of mechanics and mathematics at the University of Göttingen and received his doctorate in 1922 under Ludwig Prandtl in Göttingen. In his dissertation he showed the instability of the boundary layer of plane laminar flows on a wall, even with the smallest Reynolds numbers and very small perturbations, the stability being investigated according to a method by Lord Rayleigh ( linear stability theory ). According to Rayleigh, the flow was divided into strips, each with a linear profile and then transferred to continuous profiles, with profiles with a turning point showing instability. This ran counter to the theories prevailing at the time (and experiments that showed no turbulence below Reynolds numbers of 1000) and initially met with doubts from Prandtl, who, however, checked the result with Tietjens in different ways and for different profiles. Prandtl presented the results at a conference in Jena in 1921 and met criticism from other scientists in the field of turbulence, such as the Sommerfeld student Fritz Noether . Like the mathematician Ludwig Hopf, Tietjens blamed non-physical prerequisites for the calculation, especially the simple flow profile. Noether attributed the differences to the assumptions about wall smoothness. Progress in the problem of the onset of turbulence was soon made by Werner Heisenberg (1924) in his dissertation with Sommerfeld and the Prandtl student Walter Tollmien (1929).

After completing his dissertation, he worked for Prandtl at the Max Planck Institute for Flow Research in Göttingen. From 1941 he was a full professor for mechanics and fluid mechanics at the Technical University in Vienna (until 1945) and after the Second World War he was assigned as a professor emeritus at the Technical University of Karlsruhe , where he continued his research. His textbook on fluid mechanics based on lectures by Prandtl from 1929/1931 was widely distributed, including an English translation. In the 1960s he published another textbook on technical fluid dynamics.

Fonts

  • Contributions to the turbulence problem , yearbook Math.-Naturwiss. Faculty Göttingen 1923 (= Dissertation Göttingen)
  • Hydro- and aeromechanics, based on lectures by L. Prandtl, Volume 1: Balance and frictionless movement , Springer 1929, Volume 2, Movement of rubbing liquids and technical applications , Springer 1931
    • English translation by L. Rosenhead: Fundamentals of Hydro- and Aeromechanics , McGraw Hill 1934
  • Fluid mechanics. Basics from a technical point of view, Volume 1, Hydro- and Aerostatics. Movement of the ideal liquid , Springer 1960, Volume 2, Movement of liquids and gases , Springer 1970

literature

  • Paul Gerhard Franke, Adolf Kleinschroth: Brief Biographies Hydraulics and Hydraulic Engineering, Lipp 1991, p. 534
  • Obituary in the yearbook of the German Aerospace Society, 1972

Web links

Individual evidence

  1. ↑ Like the Orr-Sommerfeld theory from 1908, which could not find a transition to turbulence in such flows as the Couette flow with a linear velocity profile.
  2. ↑ Michael Eckert, The dawn of fluid dynamics, Wiley, 2006, p. 114
  3. ↑ Michael Eckert, Ludwig Prandtl, Springer, 2017, p. 151
personal data
SURNAME Tietjens, Oskar
ALTERNATIVE NAMES Tietjens, Oskar Karl Gustav
BRIEF DESCRIPTION German engineering scientist
DATE OF BIRTH April 23, 1893
PLACE OF BIRTH Wandsbeck
DATE OF DEATH October 23, 1971
Place of death Freiburg in Breisgau