Initial Model for Fires in the World Trade Center Towers.
Initial Model for Fires in the World Trade Center
Rehm, R. G.; Pitts, W. M.; Baum, H. R.; Evans, D. D.;
Prasad, K. R.; McGrattan, K. B.; Forney, G. P.
NISTIR 6879; 18 p. May 2002.
Fire Safety Science. Proceedings. Seventh (7th)
International Symposium. International Association for
Fire Safety Science (IAFSS). June 16-21, 2003, Boston,
MA, Evans, D. D., Editor(s), 25-40 pp, 2003.
Available from:: National Technical Information Service
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World Trade Center; computational fluid dynamics; fire
simulation; mathematical models
Based on preliminary assumptions and analysis,
mathematical models have been used to estimate the
behavior of the fires in the twin towers of the World
Trade Center (WTC) on September 11, 2001. The
hijacked-plane collision with each tower produced
significant structural damage, generated a spectacular
external fireball, and started burning within the tower.
The fuel consumed by the fireball was lost as an
ignition source, but produced a pressure pulse that
broke windows and changed the ventilation for the fires.
The subsequent fire in each tower generated a
quasi-steady, wind-blown smoke plume. The fire and smoke
behavior were simulated using the Fire Dynamics
Simulator (FDS). Comparison of the observed plume
trajectory with the simulated one allowed us to estimate
that the rate of energy supplied by the fire to the
plume was of the order of magnitude of a gigawatt (GW).
The rate of energy supplied to the plume, plus the
energy-loss rate, determine the total heat release rate
(HRR), the most important single parameter for each
tower fire. Two bounding scenarios for the interior
damage and fuel distributions were assumed for the north
tower. For each scenario, the simulated visible fire and
smoke behavior outside the tower were compared with the
photographic and video records to determine which
scenario seemed more appropriate. The simulations for
the two scenarios also provided estimates of the likely
thermal environment within each tower.