Transport by Gravity Currents in Building Fires.
Transport by Gravity Currents in Building Fires.
(855 K)
Rehm, R. G.; McGrattan, K. B.; Baum, H. R.; Cassel, K.
W.
International Association for Fire Safety Science. Fire
Safety Science. Proceedings. Fifth (5th) International
Symposium. March 3-7, 1997, Melbourne, Australia, Intl.
Assoc. for Fire Safety Science, Boston, MA, Hasemi, Y.,
Editor(s), 391-402 pp, 1997.
Keywords:
fire research; fire safety; fire science; ceilings;
building fires; heat transfer; gravity current;
computational fluid dynamics; large eddy simulation
Abstract:
Gravity Currents (GC) are important physical phenomena
which transport smoke and hot gases in corridors of
buildings. In this paper, they are studied using large
eddy simulations (LES). The transient Navier-Stokes
(N-S) equations are numerically integrated with very
high resolution, in two dimensions and with high
resolution in three dimensions. The LES computations
require no adjustable parameters, and are found to agree
well with available experimental results in the absence
of heat transfer. Fresh-water/salt-water experimental
results are compared with computational results with
adiabatic boundary conditions to demonstrate the
validity of the model. Whereas, a high-resulution
two-dimensional computation simulates very well the
gravity current with adiabatic wall boundary conditions,
significant wall heat transfer requires the
consideration of three-dimensional effects. Heat
transfer to the ceiling of a corridor from an underlying
GC produces longitudinal convection rolls which
significantly enhance heat losses to the ceiling and
reduce the speed of progression of the GC down the
corridor.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899