Wednesday, September 8, 2010

Release of FDS 5.5.2

A maintenance version of FDS has been posted to the Downloads page. This is version 5.5.2. Unless there are serious bugs to fix, this might be our last release of FDS 5. We are working on FDS 6, and those of you who participate in the group discussions will have already heard alot of chatter about FDS 6. One thing to keep in mind is that the transition from FDS 5 to 6 will be relatively transparent to most users. We are not planning on major changes to the input parameter names or file structure. The reason for changing from 5 to 6 is that there are going to be changes to the basic algorithm that warrent a change in major release number.

As always, for those of you who have submitted bug reports for FDS 5.5.1, please check that the new version fixes the problem if we have claimed to have fixed it. This is a very important part of our quality control, but unfortunately only about 1 in 10 users follow up on bug reports and actually verify that the fix has worked. Even worse, we often find out, months after fixing something, that the original submitter of the bug report continues to use the work-around that was suggested when the report was first submitted. That's not a good way to make progress.

Friday, August 6, 2010

Google moderator for FDS-SMV

Dear Group:

In an effort to better accommodate the needs of the community moving forward, we have set up a Google moderator series to help gather feedback on questions concerning FDS-SMV development.

To get things started, I have submitted a question to you, the group, regarding the default output frequency of Plot 3D (.q) files. Please vote on this idea.

Also, feel free to submit other ideas and comment on the ideas already present.

Our feeling is that this forum will help us sort developmental priorities and answer simple questions like the one presented above. We hope this will encourage participation from the community at large and that the voice of those who do not regularly chime in on the discussion group can more easily be heard.


Monday, June 14, 2010

parallel processing on the Windows command line

The purpose of this post is to explain the use of a new utility named background.exe - what it is and how it might be useful. It is available with the smokeview 5.5.5 windows installation just posted on the download site at

As you all know, MPI is a software library used to enable parallel processing at the program ie FORTRAN source code level. This enable ONE FDS job to make use of multiple CPUs thereby speeding up the calculation. It is often the case however that you are doing a parameter study or running a verification suit - ie you have a long list of FDS jobs to run. Typically you would create a windows batch file (.bat) containing a list of commands like

fds5 casename_1.fds
fds5 casername_n.fds

On a Windows system, each entry in the above list will not start until the previous entry has completed - even if your computer has multiple cores or CPUs.

Unix/Linux based systems have the capability to put a computer job in the background, meaning that when you run the job, control returns to you immediately allowing you to run another job. With computers with multiple cores or CPUS you can then run more than one job simultaneously.

I didn't see a way of doing this on a Windows system so, I wrote a little utility called background that does just that.

Here is how you might use it with FDS

background -d 1.0 -u 90 fds5 casename.fds

This command runs "fds5 casename.fds" after waiting 1 s and ensuring that the CPU usage is less than 90 %. If the CPU usage happens to be more than 90 %, "background" waits to submit the fds5 command until the usage drops below 90 % then runs fds5 casename.fds.

The purpose of the delay before submitting the job to give windows a chance to update usage from previous invocations. (not really sure if this is needed. This feature is a fail safe to enusure that a large number of jobs are not submitted at once).

The background utility is designed to use in a windows batch file. Say you have a list of 5 FDS jobs you want to run in a .bat file. On a windows computer you would have a batch file with the contents something like

fds5 case1.fds
fds5 case2.fds
fds5 case3.fds
fds5 case4.fds
fds5 case5.fds

Using background and if you accept the default you would change your script to something like

background fds5 case1.fds
background fds5 case2.fds
background fds5 case3.fds
background fds5 case4.fds
background fds5 case5.fds

(or you could add -d and -u options ) On my system, I can make use of all 4 cores cutting the run times by a factor of 4.

Type background -h to see help info. Let me know if you have any questions.

Thursday, June 10, 2010

Smokeview Maintenance Release 5.5.5

A new maintenance release of Smokeview , version 5.5.5, has been posted at . Besides bug fixes and a few other enhancements, I added a new way to manipulate the scene, inspired by a question on the users forum. Basically you can now make use of all 3 mouse buttons (on a 3 button mouse) to manipulate the scene.

LEFT – same as before – rotate the scene

MIDDLE – move in, out, left, right

RIGHT – move up and down.

The right mouse button was used for menuing. So to use the RIGHT mouse button for scene manipulation you first have to turn menuing off. Do this by press the M key . To turn menus back on press the M key again.

This feature is a work around for a problem that occurs with the Linux version of Smokeview. It did not support vertical scene movement because Smokeview could not detect the use of the ALT key.

Wednesday, April 7, 2010

FDS/Smokeview Minor Release 5.5

We have just posted a minor release of FDS and Smokeview, version 5.5. Recall that a minor release of FDS means that there will be some change in functionality related to one or more of the following:
  • More accurate properties of various gases and liquids using the JANAF Thermochemical Tables
  • Restoration of the baroclinic torque term in the momentum equation
  • Improved treatment of droplets and sprays
  • Improved treatment of various boundary conditions

You may not notice some of the changes, but because they might affect slightly some results, we decided to release these as a minor release.

Many of these improvements have come as a result of the increased verification work that we see being done by the users. Sometimes we find that very simple test cases submitted to the Issue Tracker reveal a feature of the model that is not working as well as it could. Often, these submittals have nothing to do with fire. They are fundamental thermodynamics issues. Takes us back to the good old days of engineering classes. Thanks to all of you who put together these cases and spend a considerable amount of time working with us to diagnose the problems.

In addition to new versions of FDS and Smokeview, there are updated versions of all the manuals. You'll find some work in the FDS V&V Guides related to developments we refer to as "FDS6", the next major release. We're trying to gradually work in the necessary structural changes to the code to prevent the kind of abrupt change that occurred when we transitioned from version 4 to 5. Hopefully, 5 to 6 will be smoother. We do not anticipate major changes to the input or output formats -- the major changes will be under the hood.