Qualitative visualization – Water channel of Ludwig Prandtl
In his famous lecture ‚Über Flüssigkeitsbewegung bei sehr kleiner Reibung‘ at the III. Internationaler Mathematiker Kongress in 1904, where Ludwig Prandtl introduced the concept of the boundary layer for the first time, he also described the experimental set-up of his water channel and presented photographs of vortices behind sharp edges, a curved vane and around a circular cylinder, taken after the water has been set in motion by means of a paddle wheel.
- Prandtl, L., Über Flüssigkeitsbewegung bei sehr kleiner Reibung. Verhandlungen des III. Internationalen Mathematiker Kongresses, Heidelberg 1904, pp. 484 – 491.
https://goedoc.uni-goettingen.de/bitstream/handle/1/6356/Prandtl.pdf?sequence Reprint, pp. 1-8
The description of the experiments in the water channel can be found on page 7-8 and the photographs on page 101 of the reprint.
During the Wilbur Wright Memorial Lecture given by Ludwig Prandtl in 1927 in London he illustrates the flow phenomena discussed by him by photographs taken at the visualization of unsteady flows in different water channels since 1904.
- Prandtl, L., The Generation of Vortices in Fluids of Small Viscosity (Wilbur Wright Memorial Lecture 1927). Roy. Aeron. Soc. Bd. XXXI, p 720 -743;
Z. Flugtechn. Motorl. 18. Jg, pp. 489-496.
The description of the experiments in the water channel can be found on page 751 ff. of the reprint.
By photographic recording it became possible to store images of such flow phenomena unbiased, without any (possibly subjective) interpretation by the observer of the phenomenon. The discussion how to assess the flow phenomenon based on the recorded images could be done later within the scientific community in publications or at conferences. For research qualitative visualization became of similar importance as rows of numbers of experimental data.
Prandtl's water channel of 1904 has been rebuilt by DLR Göttingen. Students of DLR's School_Lab can use the channel for experiments helping them to understand flow phenomena such as flow separation around bodies embedded in the flow in different configurations.
DLR’s School_Lab provides some further information about Prandtl's water channel (in German):
Contents provided by Juergen Kompenhans, 20171012