Fluid Dynamics Insights on Crowd Navigation Can Avert Disaster

Fluid Dynamics Insights on Crowd Navigation Can Avert Disaster
PHOTOGRAPH: Arne Müseler | Photo shows the entrance and exit ramp of the Loveparade 2010.

If you could substitute groups of people colliding with one another with large systems of interlocking particles, then you will grasp the basic idea of fluid dynamics.  Assessing the multitude of people can help in anticipating problems and dangers, like being crushed in the surging crowd.

Physicists, computer scientists, and researchers who have studied fluid dynamics can offer insights on how injuries and deaths may be averted in a crowd that has gone wild or out of control. The difference between crowds and interlocking particles that are the focus of fluid dynamics (or particle flow) is that “particles don’t have intention,” noted Dirk Helbing, researcher at the Swiss Federal Institute of Technology in Zurich.

Marine creatures may also illustrate how their human counterparts can optimize flow. To navigate their fluid environment, marine inhabitants balance their stability in the water with their maneuverability.

Imagine Yourself as an Electron

As the distance between two electrons increases, their repulsion from one another decreases. Substitute humans for electrons, and you also end up substituting time for distance, noted researchers Brian Skinner, Ioannis Karamouzas, and Stephen J. Guy.

Their finding was reported in 2014 in the journal Physical Review Letters. As a person’s time for calculation (or thinking on how best to avoid collisions) increases, the probability of that same collision decreases.

Real-Life Commotions

There is always the probable danger in a crowd. More than a thousand persons were injured, and hundreds reportedly killed during a rush in the 2006 hajj pilgrimage to Mecca.

In 2010, 500 people were injured and 21 killed in an electronic dance festival called Love Parade when attendees panicked while going through a narrow tunnel in the venue in Germany. As a crowd gets denser, there occurs what are called “stop-and-go waves” in which a person moves forward into any gap in the crowd – and then stops and waits for another such gap.

Helbing stated that the stop-and-go wave is a sign that the crowd situation has gone critical, and that at any moment, a ”black hole effect” will materialize. This means that when one person stumbles, the space he leaves gets filled up by the one behind him who also stumbles, and so on.

Advice for Concert-Goers, Rabid Protesters & Harried Commuters

The researchers offered tips on how to stay safe in a crowd. Skinner said “looking three or four seconds into the future” would help you analyze the crowd, anticipate problems, and look for a better route if necessary.

Karamouzas advised that if you spot a stop-and-go wave, it is best to get out of the crowd, especially if it is an open venue. If it is an enclosed site, trying to back out would only cause panic. Helbing concurred, “avoid going against the flow” and  he emphasized the importance of knowing where the emergency exit is.


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