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Author Topic: Initial Region Temperature vs Ambient temperature  (Read 5409 times)

Michele

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Initial Region Temperature vs Ambient temperature
« on: January 25, 2010, 04:54:59 am »

Hi,
in FDS there is the possibility of having a region with initial temperature different from ambient temperature. The code line is like the following (example from "stack_effect" in FDS)
&INIT XB=0.5,0.8,2.1,3.4,2.5,3.6, TEMPERATURE=30. /
where the region XB is associated an initial air temprature of 30°C (ambient temperature can be default or other values)
 
Unfortunately this command is not recognized when importin the FDS file in Pyrosim.

Is there the possibility of having this command/action in Pyrosim?

thanks a lot
Michele
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Charlie Thornton

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Re: Initial Region Temperature vs Ambient temperature
« Reply #1 on: January 25, 2010, 08:47:49 am »

Yes.  While that particular record isn't supported via the UI, you can still use that feature of FDS.  You can paste the input record:

&INIT XB=0.5,0.8,2.1,3.4,2.5,3.6, TEMPERATURE=30. /

Into the Additional Records portion of the record view.  PyroSim actually does this automatically when importing the file - so you probably already have that record in your additional records.

For example, if you were to import the stack_effect.fds verification problem, PyroSim will notify you that the INIT record has been added to the Additional Records section, then produce the following FDS input file:

Code: [Select]
untitled.fds
Generated by PyroSim - Version 2010.1.0928
Jan 25, 2010 8:44:18 AM

-------------User Section (not generated by PyroSim)-------------

&INIT XB=2.0000000E001,8.0000000E001,-2.0000000E000,2.0000000E000,0.0000000E000,3.0400000E002, TEMPERATURE=2.0000000E001/

--------------------PyroSim-generated Section--------------------

&HEAD CHID='untitled', TITLE='Test of Stack Effect, SVN $Revision: 2066 $'/
&TIME T_END=100.00/
&DUMP RENDER_FILE='untitled.ge1', DT_RESTART=300.00/
&MISC TMPA=10.00, RADIATION=.FALSE./

&MESH ID='Mesh', IJK=100,1,400, XB=0.00,100.00,-1.00,1.00,0.00,400.00/

&DEVC ID='DEVC', QUANTITY='DENSITY', XYZ=10.00,1.00,2.50/
&DEVC ID='DEVC02', QUANTITY='DENSITY', XYZ=50.00,1.00,2.50/
&DEVC ID='DEVC03', QUANTITY='DENSITY', XYZ=10.00,1.00,302.50/
&DEVC ID='DEVC04', QUANTITY='DENSITY', XYZ=50.00,1.00,302.50/
&DEVC ID='DEVC05', QUANTITY='U-VELOCITY', XYZ=19.50,0.00,2.50/
&DEVC ID='DEVC06', QUANTITY='U-VELOCITY', XYZ=19.50,0.00,302.50/
&OBST XB=19.00,20.00,-1.00,1.00,0.00,2.00, SURF_ID='INERT'/ Left Facade
&OBST XB=19.00,20.00,-1.00,1.00,3.00,302.00, SURF_ID='INERT'/ Obstruction #1
&OBST XB=19.00,20.00,-1.00,1.00,303.00,304.00, SURF_ID='INERT'/ Obstruction #2
&OBST XB=80.00,81.00,-1.00,1.00,0.00,304.00, SURF_ID='INERT'/ Right Facade
&OBST XB=19.00,81.00,-1.00,1.00,304.00,305.00, SURF_ID='INERT'/ Roof

&VENT SURF_ID='OPEN', XB=100.00,100.00,-1.00,1.00,0.00,400.00, COLOR='INVISIBLE'/ Vent XMAX for Mesh
&VENT SURF_ID='OPEN', XB=0.00,0.00,-1.00,1.00,0.00,400.00, COLOR='INVISIBLE'/ Vent XMIN for Mesh
&VENT SURF_ID='OPEN', XB=0.00,100.00,-1.00,1.00,400.00,400.00, COLOR='INVISIBLE'/ Vent ZMAX for Mesh

&SLCF QUANTITY='DENSITY', PBY=0.00/
&SLCF QUANTITY='DIVERGENCE', PBY=0.00/
&SLCF QUANTITY='H', PBY=0.00/
&SLCF QUANTITY='PRESSURE', PBY=0.00/
&SLCF QUANTITY='TEMPERATURE', PBY=0.00/
&SLCF QUANTITY='VELOCITY', VECTOR=.TRUE., PBY=0.00/

&TAIL /
« Last Edit: January 26, 2010, 09:19:29 am by Charlie Thornton »
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Charlie Thornton

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Re: Initial Region Temperature vs Ambient temperature
« Reply #2 on: January 25, 2010, 08:50:41 am »

I'm noticing that we need to make the number formatter for the additional records match the one for the generated records.  Fortunately, having 6 extra (useless) digits of precision won't make any difference to FDS.
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Michele

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Re: Initial Region Temperature vs Ambient temperature
« Reply #3 on: January 25, 2010, 01:45:37 pm »

So you mena that even though it is reported at the beginning (before the HEAD_CHID) it will be considered when computing the FDS?
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Charlie Thornton

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Re: Initial Region Temperature vs Ambient temperature
« Reply #4 on: January 26, 2010, 08:59:28 am »

Yes - FDS lets you mix and max pretty freely.  Just don't add anything after the TAIL record.  Here is an example:

I have a 10x10 room divided down the center by a wall.  On the left side of the wall I have specified an initial temperature at 50 C.  The right model boundary is open.  There is a hole in the lower center of the wall.  I've attached some screen shots of the results.

Code: [Select]
untitled.fds
Generated by PyroSim - Version 2010.1.0928
Jan 26, 2010 8:53:50 AM

-------------User Section (not generated by PyroSim)-------------

&INIT XB=0.0,5.0,0.0,10.0,0.0,3.0, TEMPERATURE=50. /

--------------------PyroSim-generated Section--------------------

&HEAD CHID='untitled'/
&TIME T_END=30.00/
&DUMP RENDER_FILE='untitled.ge1', DT_RESTART=300.00/

&MESH ID='MESH', IJK=40,40,12, XB=0.00,10.00,0.00,10.00,0.00,3.00/

&OBST XB=4.50,5.00,0.00,10.00,0.00,3.00, SURF_ID='INERT'/ Obstruction

&HOLE XB=4.5000000E000,5.0000000E000,4.5000000E000,5.5000000E000,0.0000000E000,1.0000000E000/ Wall Hole

&VENT SURF_ID='OPEN', XB=10.00,10.00,0.00,10.00,0.00,3.00, COLOR='INVISIBLE'/ Vent Max X for MESH

&SLCF QUANTITY='TEMPERATURE', PBZ=0.50/


&TAIL /
« Last Edit: January 26, 2010, 09:17:44 am by Charlie Thornton »
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