Pastor José M, Garcimartín Angel, Gago Paula A, Peralta Juan P, Martín-Gómez César, Ferrer Luis M, Maza Diego, Parisi Daniel R, Pugnaloni Luis A, Zuriguel Iker
Departamento de Física, Facultad de Ciencias, Universidad de Navarra, E-31080 Pamplona, Spain.
Departamento de Ingeniería Mecánica, Facultad Regional La Plata, Universidad Tecnológica Nacional, Av. 60 Esq. 124 S/N, 1900 La Plata, Argentina.
Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Dec;92(6):062817. doi: 10.1103/PhysRevE.92.062817. Epub 2015 Dec 15.
The "faster-is-slower" (FIS) effect was first predicted by computer simulations of the egress of pedestrians through a narrow exit [D. Helbing, I. J. Farkas, and T. Vicsek, Nature (London) 407, 487 (2000)]. FIS refers to the finding that, under certain conditions, an excess of the individuals' vigor in the attempt to exit causes a decrease in the flow rate. In general, this effect is identified by the appearance of a minimum when plotting the total evacuation time of a crowd as a function of the pedestrian desired velocity. Here, we experimentally show that the FIS effect indeed occurs in three different systems of discrete particles flowing through a constriction: (a) humans evacuating a room, (b) a herd of sheep entering a barn, and (c) grains flowing out a 2D hopper over a vibrated incline. This finding suggests that FIS is a universal phenomenon for active matter passing through a narrowing.
“越快越慢”（FIS）效应最初是通过对行人从狭窄出口疏散的计算机模拟预测出来的[D. 赫尔宾、I. J. 法尔卡斯和T. 维谢克，《自然》（伦敦）407, 487 (2000)]。FIS指的是这样一个发现：在某些条件下，个体在试图疏散时过度用力会导致流量下降。一般来说，当将一群人的总疏散时间作为行人期望速度的函数进行绘制时，通过出现最小值来识别这种效应。在这里，我们通过实验表明，FIS效应确实发生在三种不同的离散粒子系统通过狭窄通道流动的情况中：（a）人们从房间疏散，（b）一群羊进入谷仓，以及（c）谷物从二维料斗通过振动斜面流出。这一发现表明，FIS是活性物质通过变窄通道时的一种普遍现象。
