The Windtunnel

The Lund Wind tunnel, built in 1994. In the opening between the test section and the bellmouth the researcher operating the wind tunnel can have quick and easy access to the bird.
Aerodynamics of bird flight can be studied by several approaches. The use of wind tunnels for bird flight experiments is extremely appealing, because it enables the researcher to observe the flying bird while it is flying in the test section. Thereby, high-speed video cameras can register details of the wing motions, accelerations of the body and wake vorticity can be visualized.
Will there ever be a bird in the tunnel?
The wing of a knot, laid out to measure area.
 

We use a modern low-speed wind tunnel specially crafted for bird experiments. The bird is trained to fly in the “test-section”, where the flow is near laminar (turbulence about 0.3-0.4%, expressed as variation around the mean flow). The Lund wind tunnel can be tilted to simulate climbing flight and gliding flight, a feature which is extremely useful when studying conversion efficiency of fuel (the energy consumption of the bird is then measured in horizontal flight and with a small climbing angle), and the gliding flight performance. A description and technical account of the Lund wind tunnel is given by Pennycuick et al. (1997), and on the official wind tunnel site, here.
 
The wind tunnel building at the east entrance of the Ecology building, Lund University. Inside the wind tunnel building. The test section is encapsulated by a cage to prevent birds form escaping.


Barlow, J. B., Rae, W. H. Jr. and Pope, A. (1999). Low-speed wind tunnel testing. New York: John Wiley & Sons.

Pennycuick, C. J., Alerstam, T. and Hedenström, A. (1997). A new low-turbulence wind tunnel for bird flight experiments at Lund University, Sweden. J. Exp. Biol. 200, 1441-1449.

Rosén, M. (1999). Experimental approaches for studying vertebrate flight in a wind tunnel. Introductory Paper No. 113, Lund University.