Magically disappearing furniture in Smokeview?

[Andrea]

I am a new user to FDS - I am running into a problem with magically
disappeared furniture in Smokeview. I have a fds file that runs,
shows everything in the room and fire, but after 120 frames - the
furniture and the fire instantly disappear. I'm guessing this is due
to a burn away function, and I'm increasing my grid size in the hopes
that it will actually be visible. I am also going to try reducing the
burner size. Does burn away without ramp ID's always disappear that
fast? Or am I doing something else wrong?

Thanks in advance for any help!

Andrea

P.S. I am running FDS5 on a MacBook Pro, 2.4 GHz Processor, 4G RAM,
OS X v10.5.4

[dr_jfloyd]

Have you defined the furniture surface with material properties that
result in it burning away?

If you haven't, then this may be a bug.

If you have defined properties that burn away, double check your
inputs and make sure you have the correct units for everything (i.e.
you haven't done g/cm^3 vs. kg/m^3 or the like).

[Andrea]

To be honest, since I am still learning, I was cutting and pasting
materials values out of existing, functional, fds runs. The materials
all work fine in the files they came from. I will try switching burn
away to false to see if it change anything.

Thanks for the quick response!

[Andrea]

So I turned BURN_AWAY to FALSE on all my SURF files, and my furniture
stopped disappearing in Smokeview, my flame also came back since it
had something to burn! Forgive the uninitiated, but does that mean
this is a bug? Or does that mean I have a funky material value in
there somewhere?

FDS v5.1.0 Revision: 1162

[Bryan Klein]

It means you were misusing a feature of FDS.

Please make sure to read the FDS User's Guide.
-Bryan

[Andrea]

Sorry,

Victim of bad information - I am in a class (very, very basic) and was
told that burn away would cause the object to disappear cell by cell,
not all at once. I tried reading the User's Guide, but it's hard when
starting from absolutely no knowledge whatsoever...also my class is
teaching FDS4 - I am the only student using 5! This is my second time
ever modeling a fire - I figured it was me, but someone mentioned a
possible bug, which is why I posted the second question!

Thank you for taking the time to respond - sorry my questions are so
basic.

Is there a better place for me to post questions about what are most
likely "pilot" errors? I don't want to post new user questions here
if this is a board for advanced users.

[BlairS]

Your mesh size may have been large enough that each item of
'furniture' comprises only 1 or 2 grid cells. This would account for
the sudden disappearance of your object. Using burn_away with smaller
grid cells (say, 0.1 m) would generally result ina more gradual
disappearance of your object. Try running the test case that comes
with the FDS install ('box_burn_away.fds').

As an aside new users can generally get a lot of help from this forum
IF they start their question with "I have read section xxx of the
user's guide, and searched the forum for these keywords..., and I
still don't understand some feature" or "This doesn't appear to be
covered in the user's guide". The response you get will be a lot more
helpful if people think you've tried to find out yourself first.
Indeed if the guide isn't clear the developers need to know what
you're having difficulty with.

Good on you for using FDS5, it should place you ahead of your
classmates when you get to the real world - in my experience
authorities generally expect the latest version of the model to be
used for design work.

Regards,
Blair Stratton
Beca

> > >>>> OS X v10.5.4- Hide quoted text -
>
> - Show quoted text -

[Andrea]

Blair,

Thanks for the hints - I did have a 0.1 mesh, but I think my HRR was
so high from my burner that it basically vaporized my furniture! I'm
going to try ramping my burner (which would be more realistic anyway)
and see if that changes things. The box burn appears to work, so I
must have a line wrong in there somewhere. I also moved it to a 0.05
mesh - we'll see what happens.

Thanks again for the help,

Andrea

[Bryan Klein]

Your problem has changed over time. Initially it seemed that the
problem was that you were using the burn away function when you did not
intend to. Now, it seems that you intended to use it, it is just not
behaving as you expected. This is a different issue altogether.

When you encounter odd behavior like this, it is better to post to the
Issue Tracker. There you can attach your input file and explain your
problem. Take a look at:
http://code.google.com/p/fds-smv/wiki/EffectiveIssuePosting

I am curious about your input file, it would be interesting to see a
whole solid object burn away in a single time step.

-Bryan

[Andrea]

Bryan,

I was running it as a very short file - trying to get the bugs worked
out without running for hours, so I am wondering if that has something
to do with it - I will gladly post the file to Issue Tracker. I only
asked here first because I thought it was me just making a rookie
mistake!

I'll post it right away and gladly let the experts review it. My
instructor said he'd never seen it before either!

You guys are awesome - thanks again for all the input! It helps when
learning this new language!

Andrea

P.S. I know you use a Mac too - what format do you put your input
files in when transferring them to WIndows machines? I have been
typing input files in TextEdit and saving them as Unicode (changing
extension to .fds when I am ready to run them), but when they are
opened on a Windows machine it does not preserve the tabs or carriage
returns. Should I be using something else?

[Andrea]

...and after reviewing the file and slowing it down to 4 x real time I
did indeed see the furniture burn away....in 3 frames! So lesson
learned, burn away + short simulation + high heat release rate = no
more furniture. Sorry for the confusion, I will not post to Issue
Tracker, since obviously, I was the issue!!

Thanks again for all the help!

[Kristopher Overholt]

TextEdit works in rich text mode by default, but it can work with plain text files as well. From MacRumors.com:

"By default, TextEdit saves documents in rich text format. This is unsuitable for some situations, such as when creating a hand-coded html file. As a solution, a document can be converted to plain text by choosing Format > Make Plain Text. Alternatively, you can set TextEdit to create all new documents as plain text by setting the new document format to "Plain Text" in the preferences."

When working with FDS files on my Mac, there are a couple of other choices for plain text editors that pack some extra useful features of their own. The two that I use and that are very popular in the Mac world are TextWrangler (free) and Textmate (not free but very worth registering). If you use these programs to work with plain text FDS files they will work fine on Windows or Linux and you will get to utilize extra features like syntax highlighting and code completion.

Hope that helps.

Kristopher

--
Kristopher James Overholt
Fire Protection Engineering Graduate
University of Houston-Downtown

[Bryan Klein]

Not only are you the only one in the class using FDS_5, but you are
using a Mac... it doesn't get much better than that in my opinion. :)
I made a screencast about using FDS and SMV in OSX.
http://fire.nist.gov/fds/assets/video/FDS-SMV_on_OSX.mov
Have you seen it?

On Thu, Jul 17, 2008 at 1:38 PM, Andrea <prett...@usmac.net> wrote:

> I'll post it right away and gladly let the experts review it. My
> instructor said he'd never seen it before either!

No need to post, sounds like you had created a non-physical scenario
and FDS was doing what you asked it to do. Just because the
simulation runs does not mean that it reflects reality.

> P.S. I know you use a Mac too - what format do you put your input
> files in when transferring them to WIndows machines? I have been
> typing input files in TextEdit and saving them as Unicode (changing
> extension to .fds when I am ready to run them), but when they are
> opened on a Windows machine it does not preserve the tabs or carriage
> returns. Should I be using something else?

I don't do anything special when saving. Plain text (ASCII) is the goal.

As Kris also mentioned, I too use TextWrangler and TextMate for FDS input files.
http://www.barebones.com/products/textwrangler/
http://macromates.com/

One cool tip for both of these apps., Check out the ALT+Click+Drag select mode.
It really helps when replacing columns of characters. Here are a few
tips for using TextMate, the Column Selection example is what I am
talking about here.
http://www.thinkvitamin.com/reviews/dev/textmate
I am sure you can see how useful this can be when used with a highly
structured text file like FDS input files.

Usually in Windows if your use WordPad instead of Notepad for FDS
files, the end of line and tab characters are read correctly.

--
Bryan Klein
bryan...@nist.gov

National Institute of Standards and Technology
100 Bureau Drive, Mail Stop 8663
Gaithersburg MD 20899
Phone: 301 975 5171
Fax: 301 975 4052

[Andrew Louie]

all this talk of text editor's just reminded me.
I wrote a short perl script that generates a VIM syntax file that
provides syntax coloring for FDS input files.
its in the files area: fds_make_syn.pl

just run it in a directory that contains the read.f90 source code.if
you don't have the read.f90 file, just download it from the source
code area.

The script will read all the namelist lines in the read.f90 file so it
will get all the keywords, and you'll always have an up-to-date syntax
file as long as you have an up-to-date read.f90 source file, unless
the developers change how this part of the program works.

The script will generate a syntax file, you can use with VIM to get
pretty colors. The syntax file also tells VIM to highlight obsolete
FDS_4 namelist groups in red. useful if you're converting from FDS_4
to FDS_5

--
-Andrew Louie :wq
--雷恩銘

[Andrea]

Thanks for the screencast link - it helped my get the launcher running
again when I downloaded the newest Smokeview version!! Did I mention
how much I love the drag and drop running of Smokeview? It's a
beautiful thing! I also created the dual dock ports for the launcher
- that was a great tip - I was getting frustrated only being able to
run one at a time!

I forwarded the info about using WordPad instead of Notepad to the
rest of my class, maybe the instructors will change that in the
curriculum.

Thanks again for all the info!!

Andrea

On Jul 17, 5:21 pm, "Bryan Klein" <bryanwkl...@gmail.com> wrote:
> Not only are you the only one in the class using FDS_5, but you are
> using a Mac... it doesn't get much better than that in my opinion. :)

> I made a screencast about using FDS and SMV in OSX.http://fire.nist.gov/fds/assets/video/FDS-SMV_on_OSX.mov
> Have you seen it?

>
> On Thu, Jul 17, 2008 at 1:38 PM, Andrea <prettytr...@usmac.net> wrote:
> > I'll post it right away and gladly let the experts review it.  My
> > instructor said he'd never seen it before either!
>
> No need to post, sounds like you had created a non-physical scenario
> and FDS was doing what you asked it to do.  Just because the
> simulation runs does not mean that it reflects reality.
>
> > P.S.  I know you use a Mac too - what format do you put your input
> > files in when transferring them to WIndows machines?  I have been
> > typing input files in TextEdit and saving them as Unicode (changing
> > extension to .fds when I am ready to run them), but when they are
> > opened on a Windows machine it does not preserve the tabs or carriage
> > returns.  Should I be using something else?
>
> I don't do anything special when saving.  Plain text (ASCII) is the goal.
>

> As Kris also mentioned, I too use TextWrangler and TextMate for FDS input files.http://www.barebones.com/products/textwrangler/http://macromates.com/

>
> One cool tip for both of these apps., Check out the ALT+Click+Drag select mode.
> It really helps when replacing columns of characters.  Here are a few
> tips for using TextMate, the Column Selection example is what I am

> talking about here.http://www.thinkvitamin.com/reviews/dev/textmate

> I am sure you can see how useful this can be when used with a highly
> structured text file like FDS input files.
>
> Usually in Windows if your use WordPad instead of Notepad for FDS
> files, the end of line and tab characters are read correctly.
>
> --
> Bryan Klein

> bryan.kl...@nist.gov