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Simulation of Fires With Radiative Heat Transfer.

Simulation of Fires With Radiative Heat Transfer.
(723 K)

Mell, W. E.; Baum, H. R.; McGrattan, K. B.

International Conference on Fire Research and
Engineering (ICFRE2), Second (2nd). Proceedings.
National Institute of Standards and Technology (NIST)
and Society of Fire Protection Engineers (SFPE). August
3-8, 1997, Gaithersburg, MD, Society of Fire Protection
Engineers, Boston, MA, 26-36 pp, 1998.

### Keywords:

fire research; fire protection engineering; radiative
heat transfer; simulation; thermal radiation; transport
equation

### Abstract:

*
Thermal radiation is the dominant mode of heat transfer
in very large fires. Even in small pool fires (diameter
of 0.1-0.3 m) radiative feedback to the fuel surface is
significant. The purpose of this paper is to describe a
model of radiative transport in gases that is suitable
for use with a large eddy simularion (LES) approach for
fire dynamics developed at NIST. This LES model of
convective transport and combustion heat released was
developed by distinguishing between physical processes
that can be explicitly computed and those that operate
at length and time scales too small to be resolved
(i.e., subgrid). The same strategy will be attempted
here for the thermal radiation generated by the fire.
The starting point is the radiative transport equation
for gases. For the present purposes it is sufficient to
understand that the fluid mechanics is calculated on an
Eulerian finite difference grid in rectangular
coordinates. The velocity and temperature fields so
calculated are assumed to be large scale phenomena
resolvable on the grid. The combustion phenomena that
drive the flow are assumed to be of subgrid scale, whose
consequences can be represented by Lagrangian "thermal
elements". These elements release sensible energy into
the gas as they are convected with the large scale fluid
motion.
*