Fire Dynamics Simulator (Version 4): Technical Reference Guide.
Fire Dynamics Simulator (Version 4): Technical
Reference Guide.
(625 K)
McGrattan, K. B.
NIST SP 1018; NIST Special Publication 1018; 94 p.
July 2004.
Keywords:
dynamics; simulation; scenarios; hydrodynamic model;
combustion; thermal radiation; sprinklers; validation;
sensitivity
Abstract:
The use of fire models currently exteI1lds beyond the
fire research laboratories and into the engineering,
fire service and legal communities. Surveys of available
fire models have been compiled and show a significant
increase in the number of available models over the last
decade. Sufficient evaluation of fire models is
necessary to ensure that those using the models can
judge the adequacy of their technical basis,
appropriateness of their desired use, and confidence
level of their predictions. This document provides the
theoretical basis for the Fire Dynamics Simulator (FDS)
and a summary of the work performed to verify and
validate the model. Such evaluations of fire models
prevent their unintentional misuse. This guide is based
in part on the "Standard Guide for Evaluating the
Predictive Capability of Deterministic Fire Models,"
ASTM E 1355. ASTM E 1355 defines model evaluation as
"the process of quantifying the accuracy of chosen
resu1ts from a model when applied for a specific use."
The model evaluation process consists of two main
components: verification and validation. Verification is
a process to check the correctness of the solution of
the governing equations. Verification does not imply
that the governing equations are appropriate; only that
the equations are being solved correctly. Validation is
a process to determine the appropriateness of the
governing equations as a mathematical model of the
physical phenomena of interest. Typically, validation
involves comparing model results with experimental
measurement. Differences that cannot be explained in
terms of numerical errors in the model or uncertainty in
the measurements are attributed to the assumptions and
simplifications of the physical model. Evaluation is
critical to establishing both the acceptable uses and
limitations of a model. Throughout its development, FDS
has undergone various forms of evaluation, both at NIST
and beyond. This guide provides a survey of work
conducted to date to evaluate FDS. Roughly half of the
referenced studies were aimed primarily at model
evaluation, the other half describe limited work to
validate FDS for a specific use. The latter group were
performed mostly by practicing engineers who did not
have the time or resources to comprehensively evaluate
the model. Collectively, the body of work forms the
basis of a model evaluation. As FDS development
continues, the work performed to date will provide a
framework for future research.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899