Collisions Engineering: Theory and Applications by Michel Frémond

Author:Michel Frémond
Language: eng
Format: epub
Publisher: Springer Berlin Heidelberg, Berlin, Heidelberg

Table 6.5Evacuation of room—average flow rate Q (ppl/min) of pedestrians leaving through the exit

Simulations or real-life experiment

Q (ppl/min)

s

s

s

Simulations with adapted DEM approach

182

182

181

Simulations with adapted NSM1 approach

279

276

278

Simulations with adapted NSM2 approach

156

154

155

Real experiment

160

In Table 6.5, one can see that the influence of the chosen time step on Q is negligible, as long as the temporal integration scheme is stable. In addition, one can observe that the value of Q obtained with the adapted NSM2 approach is very close to the value acquired from the emergency evacuation exercise. The pedestrians evacuate faster with the adapted NSM1 approach than with the other two approaches. These results are likely due to the manner of handling contact: perfectly inelastic for the adapted NSM1 approach, and elastic for the adapted DEM and NSM2 approaches. For these last two approaches, the difference between the values of Q could be caused by the phenomenon of overlapping, necessary for treating contact in the adapted DEM approach. Thus, in order to take into account pedestrians bumping into each other, it seems necessary to employ elastic collisions.

Evacuation of a Classroom

In this section, we will compare between a real-life exercise of a classroom evacuation and numerical simulations. The evacuation exercise, with a classroom of 30 students, is presented in [41]. The width of the classroom is 5.85 m and its length 6.75 m. The room contains 30 desks, organized into six rows and five columns. The longitudinal and transversal distances between the desks are, respectively, 0.9 and 1.35 m. The only door for entering or exiting the room is 0.5 m wide. The evacuation exercise is recorded by two video cameras. At the signal of the cameraman, all of the students stand up from their chairs and rush towards the exit. The parameters used in the numerical simulations are given in Table 6.6. Some of these parameters are uniformly distributed within a given interval. Fifty simulations have been realized.Table 6.6Evacuation of a classroom—parameters used in the simulations (uniformly distributed within the given interval); the response time is the time necessary for student i to begin evacuating after the start of the evacuation movement

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