Justin Williamson²
Jason McGill²
Zhixin Hu¹
Andrew Kohout¹
Arnaud Trouvé^1,2

Direct and Large-Eddy Simulation for Fire Safety Applications

The objective of this poster presentation is to provide an illustration of the application of advanced fluid mechanics solvers and high-performance computing resources to the simulation of fire events.  The physical ingredients present in fire configurations are similar to those found in many thermal engines, as used for propulsion or power-generation applications.  In addition to the traditional complexities found in describing turbulence-combustion interactions, fire problems feature specific difficulties that make them a challenging multi-physics and multi-scale problem.  The list of fire-specific technical difficulties include: the development of often moderately-turbulent, buoyancy-driven flow motions; the emission of fuel as a result of often poorly-understood or poorly-characterized thermal degradation processes (pyrolysis) taking place in flammable (liquid or solid) materials; the development of multi-mode (partially-premixed) combustion during fire spread (in the form of flash fires, fireballs, explosions, etc.); the occasional development of under-ventilated combustion with flame extinction events and large emissions of carbon monoxide; the emission of large quantities of soot; the large impact of thermal radiation transport; the gradual weakening of solid structures exposed to fire leading to possible failure.

Our objective in this poster is to present some examples of advanced numerical simulations applied to fire problems.  The examples include small-scale, research-level problems treated with a direct numerical simulation (DNS) approach, and large-scale, engineering-level problems treated with a large eddy simulation (LES) approach.  The DNS solver used in this presentation is a high-order finite-difference parallel solver, called S3D, developed by a DOE-sponsored collaborative program between University of Maryland, University of Michigan, University of Wisconsin and Sandia National Laboratories.  The LES solver used in this presentation is a second-order finite-difference parallel solver called the Fire Dynamics Simulator (FDS), developed by the National Institute of Standards and Technology (NIST) and oriented towards fire applications.  The S3D examples will focus on the physical details observed during turbulent flame-wall interactions.  The FDS examples will focus on large-scale, unconfined fuel vapor cloud explosions, with a focus on flash fires and fireball events.

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