FDS Database File

[Kevin McGrattan <kevin.mcgrattan@nist.gov>]

All

We get many comments/questions/complaints about the contents
of the ``database file''
which is part of the FDS/Smokeview release. In the latest
release, the file is
called ``database2.data'' and it sits in a directory usually
called 
c:\nist\fds\database2
We want to re-emphasize that the thermal property data
contained within this file
are meant to serve as examples. Anyone using this data
assumes the responsibility
of checking that it is appropriate for a particular
application, for example
1. checking the source of the data if it is given,
2. deciding if the test method used to obtain the data is
appropriate,
3. doing a few simple calculations to verify that the
numerical grid is appropriate
   for the physical phenomena being modeled,
4. doing sensitivity analyses on the parameters to determine
how sensitive are
   your results to variations in the input parameters. This
is particularly
   important when dealing with flame spread and fire growth.
What is ``appropriate'' and what is not is subject to
interpretation and good
engineering judgment. Much of the FDS development work that
we do at NIST is aimed
at ``verification,'' that is, whether the equations in FDS
are appropriate and
that they are being solved 
correctly. ``Validation'' is the process by which FDS
predictions are compared
with experimental measurements to see if the equations being
solved actually
simulate reality. We at NIST, our grantees, and FDS users
all do validation work,
but never enough to cover the entire spectrum of
applications. Many of the 
projects that we hear about have some feature for which the
code has not been
extensively validated. The equations being solved by FDS may
be appropriate for the
problem, but is up to the user to validate the choice of
input parameters. Almost
always the materials involved are more complicated than
those listed in the
database file, and the user has to decide whether or not the
physical models
within FDS are reasonable, and whether the chosen thermal
properties simulate
reality to whatever degree of accuracy demanded by the
stakeholder.

A reminder -- a working version of FDS, called FDS 2.2, is
available at
ftp://ftp.nist.gov/pub/bfrl/mcgratta/FDS2.2
Updates to the manuals are also here. For those of you
having trouble with
some aspect of the official release (2.0) may want to try
2.2. Those not
experiencing trouble with 2.0 may want to stay until we
officially release
2.2 (or whatever version number we decide to stick on it)
later this year,
probably in the summer.

Kevin



-- 
Kevin McGrattan
National Institute of Standards and Technology
100 Bureau Drive, Stop 8663
Gaithersburg MD 20899-8663

Telephone: (301) 975 2712
FAX:       (301) 975 4052