The physics of squeezing sheep through a bottleneck

The meeting on Física de sistemas fuera del equilibrio, on November 20, 2012 in Madrid, featured a talk by Iker Zurigel about sheep flowing through a bottleneck, a phenomenon which in some ways is like ketchup flowing through a bottleneck, and in some ways is not. Here’s the abstract (thanks to investigator Mason Porter and colleagues for bringing it to our attention):

Flow of sheep through a bottleneck. Effect of the presence of an obstacle

zuriguelby Iker Zuriguel [pictured here] and Angel Garcimartın, Universidad de Navarra, Pamplona.

There are times when mobs have to pass through a bottleneck, such in the case of an emergency exit. If panic seizes the crowd, a jamming can obstruct the way out. This phenomenon displays many features that are also observed with inert particles (e.g. sand, cereal) when they choke the exit of a silo or clog pipe. Recent research has lead to the discovery that an obstacle before the exit of a silo relieves the pressure near the orifice and the jamming probability decreases. Although there are some works that suggest that this method is also valid to reduce the likelihood of clogging for live beings, it is a matter of fact that the procedure has not been definitively proved. In this talk, recent experimental results of the flow of sheep through bottlenecks will be presented and compared with already existent computer simulations. In addition an analogy with the case of silo clogging will be introduced revealing the strong connection between these two apparently different scenarios.

November can be a big month for lively science meetings. This November, 2013, will see a much anticipated session (on Sunday the 24th) about Birth-Fluid Dynamics, and the Splashy Hydrodynamics of Urination, at a conference in Pittsburgh.

BONUS (quasi-related): One observer’s recommendation, in a video, that you watch a (different) video about a newfangled way to make ketchup flow:

BONUS [April 19, 2014]: A photo of sheep flowing through a bottleneck in Ireland.(Thanks to Rob Szczerba for bringing this to our attention.)