Birds are cool in so many ways!
In addition to being living descendants of dinosaurs, and being able to fly (match that, you puny apes!), they build incredible nests. There are a lot of different nests, some flimsy, some incredibly durable, all built quickly from available materials in a variety of locations, many accessible only via flight.
How do they do it?
This spring a team of researchers at the University of Akron and the University of Illinois report on computational studies (at the National Center for Supercomputing Applications, of course) of Mechanics of randomly packed filaments .
As they note, birds have evolved the ability to “mechanically synthesize multifunctional meta-materials to suit their needs” (, p. 2). “[H]umans are only beginning to understand “ the physics of these brilliant disorderly structures.
The paper summarizes the phenomenon of “jamming”, which emerges “from a subtle interplay between geometry, elasticity, and friction between its slender, flexible elements.” (p. 3) They are working to develop theories of how thin flexible materials interact, how aggregations work, and other aspects of this “birds nest” technology.
The study examines statistics of these assemblies. They note that there have been studies of “particles” and of “fabrics”, which are not well integrated. In fact, materials can be any shape, and there is no clear boundary between a particle and a fiber, a stick and a string.
The physics is very complicated, and there is little theory to describe the systems. This is a job for computational simulations! The researchers describe an array of simulations that can be used together to design and evaluate alternative “nest” structures. Not only simulations, but and integration of many simulations. This is a job for NCSA!
“This vast space can hardly be explored experimentally. Hence the need for predictive and efficient numerical models to complement and systematically integrate necessary experiments.” (, p. 7)
An illustration of what might be done is visible in the work of researchers at the University of Stuttgart were inspired by the apparently random assembly of some nests. They developed the ICD Aggregate Pavilion, displayed in 2018 .
The Stuttgart structure is build of calthrop-like pieces, dropped into place in a mold. They settle by gravity, forming a sort of solid material. As the video shows, the human-sized pavilion stands up on its own.
I notice that the person scrupulously avoids contact with the rather dangerous looking walls. How well would they stay solid if someone touches them? Or if a breeze blows? Inquiring minds want to know!
- K. Dierichs and A. Menges, ICD Aggregate Pavilion 2018, in Institute for Computational Design and Construction, 2018. https://www.icd.uni-stuttgart.de/projects/icd-aggregate-pavilion-2018/
- N. Weiner, Y. Bhosale, M. Gazzola, and H. King, Mechanics of randomly packed filaments—The “bird nest” as meta-material. Journal of Applied Physics, 127 (5):050902, 2020/02/07 2020. https://doi.org/10.1063/1.5132809