The project began in March 2014 with a visit to the DLR School Lab in Göttingen, Germany. The lab has a reproduction of Prandtl's original test channel. Inspired by the visit and bringing in their own ideas the ADP group (Andreas Bauer, Christoph Schäfer, Matthias Schäfer, Christian Wolf) has developed a channel in which water circulates horizontally in an acrylic glass track.
The channel is about the size of a table and can be used to demonstrate basic flow experiments during the technical fluid mechanics lectures of Prof. Cameron Tropea and to visualize them in the lecture hall. The group was supported and supervised by Tim Gelhaar from the SLA workshop and the research assistants Daniel Freudenhammer, Rüdiger Röhrig and Florian Wassermann.
Particle paths on the lecture hall screen
The flow is generated by a paddle wheel that can be propelled either by an electric motor or a crank. To visualize the flow, the water is seeded with aluminium particles which remain on the surface and reflect the light. A black and white camera with a suitable lens records the image from above the track.
Adjusting the frame rate and exposure time, the reflecting aluminium particles get a motion blur during the flow experiments and can be observed as particle paths. This helps students to better understand the somewhat “dry” theory behind the phenomena.