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Fire Dynamics Simulator
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Inconsistency : Drop of surface temperature and Increase of internal temperature #1119

Closed gforney closed 9 years ago

gforney commented 9 years ago 
Please complete the following lines...

Application Version:FDS 5.5.0
SVN Revision Number:6004
Compile Date: Mon 25, Apr. 2010
Operating System: Windox XP

Describe details of the issue below:

This issue is related with ID#1137 and I want to issue as a new one to avoid some confusion.
An electric panel is located inside fire zone and the internal temperature of electric
panel was checked. 
The internal surface temperature and the inside vacant temperature were analyzed by
use QUANTITY=TEMPERATURE, THERMOCOUPLE respectively.

By the way, the internal surface temperature has dropped to 20C to zero, and the vacant
temperature has increased in a great deal as shown on the attchment #1.

Please give some comments for this extraordinary phenomenon.

Thanks for some comments on the input file or any advice.

Original issue reported on code.google.com by jmhak1 on 2010-07-06 06:38:07

gforney commented 9 years ago 
I add an input file with shortest as far as I can.

Original issue reported on code.google.com by jmhak1 on 2010-07-06 06:42:40

gforney commented 9 years ago 
The case is too complicated, and it appears that you do not understand what ZONE is
for. The single line

&ZONE /

tells FDS that the entire room is one connected pressure zone. Is that true? If not,
you will see unusual effects. I still see no OPEN boundaries, in which case you might
run into unusual effects because the system is completely closed.

Do the following: take everything out of your input file and then slowly add things.
I cannot debug this case. I don't understand what you are trying to do. Start slowly
and build, and read more about ZONE.

Original issue reported on code.google.com by mcgratta on 2010-07-06 14:01:47

gforney commented 9 years ago 
Hello, Dr. McGrattan.

I assumed the entire room as one zone.

And there is an OPEN boudary at walls for fresh air intake and at ceiling for smoke
removal.
Let say, in the input of the exterior wall, I installed four(4) push type openings
by use of &VENT, XB=..., SURF_ID='supply grill', DEVC_ID='supply timer'/
It means that fresh air is supplied through wall VENTS by forced push type ventilation
(i.e., VOLUME_FLUX=-0.543) and the smoke is exhausted through the ceiling VENTS by
forced pull type ventilation (i.e., VOLUME_FLUX=0.543).

By the way there is some point in FDS user guide, that is, "Note that a HOLE has no
effect on a VENT or a mesh boudary. It only applies to OBSTrctions."
In fact, I installed all the supply and exhaust VENTs on the exterior boundary (mesh
boundary), and the Control device was used to operate the VENTS at TIME, SETPOINT designation.
Is there any mistake here?

I am sorry to drag this question too long. But I spent nearly 3 weeks to this problem
without any breakthoughs.
Thank you Sir.

* I added the particle injection view at time=70 seconds at 4 vertical walls.

Original issue reported on code.google.com by jmhak1 on 2010-07-07 01:53:44

gforney commented 9 years ago 
I see no OPEN vents in your input file.

Original issue reported on code.google.com by mcgratta on 2010-07-07 12:10:21

gforney commented 9 years ago 
If there is no OPEN vents, how can I get the figure that shows the particles injected
to the fire zone (please see the view at my attached file in previous comments).

Now, I strongly can say that there is something wrong at FDS version 5.5.0. The reason
for my instance is that, at FDS 5.5.1 win64, the phenomenon of temperature decrease
did not happen at intermittent check during my sample file running. But I am not sure
the other results for variances are reasonable or not.

Original issue reported on code.google.com by jmhak1 on 2010-07-08 00:42:31

gforney commented 9 years ago 
When I say OPEN vent, I mean

&VENT XB=..., SURF_ID='OPEN' /

This VENT is applied to the exterior boundary of the computational domain, and it allows
passive air movement in and out of the domain. If you do not have it, then your domain
is sealed, and you must exactly balance forced inflow and outflow or else you will
get a pressure rise or drop, and the associated rise or drop in temperature according
to the ideal gas law. 

If you are certain that there is a bug in the code, create a simple input file that
clearly demonstrates the problem. Take away all the obstructions except those that
are essential. Leave SLCF and DEVC lines that show the problem.

Original issue reported on code.google.com by mcgratta on 2010-07-08 11:58:58

gforney commented 9 years ago 
In other input file, I used &vent XB=....., SURF_ID='OPEN/ at exterior wall and I confirmed
the temperature decline as soon as I ran the program.

Now, FDS 5.5.1., I am running all my files withoud such temperature decline. In this
consequence, I rather ask you to use my present file at FDS 5.5.0 and FDS 5.5.1. only
for 5 seconds each. 
In fact, I do not want to waste time to argue the program itself.

Original issue reported on code.google.com by jmhak1 on 2010-07-09 03:25:35

gforney commented 9 years ago 
If the case is running properly in FDS 5.5.1, why should we run the case in 5.5.0?

Original issue reported on code.google.com by mcgratta on 2010-07-09 12:28:46

gforney commented 9 years ago 
As you know FDS 5.5.1 was recently issued. At that time, the latest version was 5.5.0.
Anyway, thanks for your attention.

Original issue reported on code.google.com by jmhak1 on 2010-07-13 04:09:47

gforney commented 9 years ago 
Your welcome.

Original issue reported on code.google.com by mcgratta on 2010-07-13 11:58:45