A Multi-Grid Model for Evacuation Coupling with the Effects of Fire Products

In the study, influences of fire products on pedestrians are introduced into a multi-grid evacuation model, in which the space is discretized into small grids with the size of 0.1 m x 0.1 m and each pedestrian occupies 5 x 5 grid sites. The fire products affect two walking parameters of pedestrians: the desired movement direction and the step frequency. The data of fire products are obtained from the simulation results of the Fire Dynamics Simulator (FDS), a well-founded computational fluid dynamic (CFD) program, developed by the National Institute of Standards and Technology (NIST). With this model, we investigated the routes of pedestrians in fires, and the evacuation times in scenarios with different fire intensities, pre-movement times or door widths. The results indicate that pedestrians will avoid moving towards the fire source, small fire may make egress process faster while large fire may reduce evacuation efficiency significantly, the movement time increases rapidly with the increasing pre-movement time, and the door width plays a more important role for evacuation in fire than normal condition. Furthermore, for the evacuation from a hall with two exits our model can reproduce the inefficient use of exits and predict the optimal condition that results in least evacuation time.