FDS Release 5.1

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

All

We have posted a new version of FDS, bundled along with the current version of Smokeview, on the Downloads page of the web site 
(fire.nist.gov/fds).  The new FDS is labelled 5.1.0 because we have changed the functionality of the multi-mesh version of the 
model.  This means that some input files that worked in FDS 5.0.x will no longer work.  There is a detailed discussion of the change 
in the FDS Users Guide, but very briefly, the change involves how meshes are connected together.  Previously, FDS allowed multiple 
meshes to overlap, abut, or not touch at all.  This is still the case, but now the mesh cells must be more carefully aligned.  The 
new restriction was necessary to improve the exchange of mass and energy between meshes.  Trying to interpolate information for 
arbitrarily connected meshes was becoming too difficult, and would ultimately prevent us from exploring new ideas such as adaptive 
meshing.  So those of you who use the new version should check that your meshes are aligned in accordance to the simple rules set 
out in the User's Guide section on meshing.

With 5.1, we have rebuilt the self-installation packages for the various operating systems.  Even if you've already installed FDS 5, 
you might want to re-install the new package.  FDS 5.1.0 also addresses bugs reported since 5.0.3.  No need to uninstall or reboot 
if you do not want to.  Your machine has all the necessary paths already set up, and the re-install will just over-write current 
files and documents. If you want to save an older version, just rename it something other than fds5.exe or smokeview.exe (Windows 
users).  Mac and Linux users can customize the installation manually if you like.  Vista users might want to think about installing 
FDS/SMV somewhere other than C:\Program Files\... as we've heard reports that Vista restricts your access to these directories. 
NIST will not allow us to install Vista.

A word about bug reporting.  Thanks to all of you who are keeping us on our toes with bug reports.  However, we would really 
appreciate it if obvious, clearly identified bugs be submitted directly to the Issue Tracker, whose link is at the left of the home 
page.  The Discussion Group is great for miscellaneous chat about all things related to FDS, Smokeview, and even fire in general, 
but if you really want a problem fixed, submit to the Issue Tracker.  Then we can assign someone to work on it until it is done. 
For example, Issue 201, first submitted on Oct 10, just after the initial FDS/SMV release, ultimately led to the changes leading to 
FDS 5.1.  It is actually a series of bugs, all related, that we worked on until completion.  The Issue remains Open until a new 
version of FDS is released and the original submitter Verifies that the problem is fixed.  Threads in the Discussion Group fall out 
of sight (and out of mind!) after a few days.  Issue Trackers do not, and these Open issues are good to check if you have any 
problems running FDS or Smokeview.

Kevin

Kevin McGrattan
National Institute of Standards and Technology
100 Bureau Drive, Mail Stop 8663
Gaithersburg MD 20899
Phone: 301 975 2712
Fax:       301 975 4052