Fire Simulation for Engineers/FDS/General Configuration
First, general configuration is performed.
The case receives a name via the HEAD
namelist group, the simulation time is set via the TIME
namelist group. Other miscellaneous parameters are prescribed via the MISC
namelist group.
Naming the job, HEAD
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The first thing to do when setting up an input file is to give the job a name. The name of the job is important because often a project involves numerous simulations in which case the names of the individual simulations can help organize the effort. The namelist group HEAD
contains two parameters, as in this example:
&HEAD CHID='mycase', TITLE='This is a short description' /
CHID
is a string of 30 characters or less used to name the output files created by FDS. No periods or spaces are allowed. TITLE
is a string of 60 characters or less that describes the simulation. It is simply a descriptive text that is passed to various output files.
It is always convenient to exactly use the same string for the name of the input file and the CHID
. For example, if you name mycase.fds
the input file, then set CHID='mycase'
in the HEAD
namelist group.
Only one HEAD
line can be entered in the input file. The following table summarizes some of the most used HEAD
parameters.
Parameter | Type | Description | Unit | Default |
---|---|---|---|---|
CHID
|
String | Job identifier | 'output'
| |
TITLE
|
String | Short description of the job |
Simulation time, TIME
[edit | edit source]TIME
is the namelist group that define the time duration of the simulation. Usually, only the duration of the simulation is required on this line, via the parameter T_END
. The default is 1 s.
For example, the following line will instruct FDS to run the simulation for 5400 s:
&TIME T_END=5400. /
If T_END
is set to zero, only the set-up work is performed, allowing you to quickly check the geometry in Smokeview.
Only one TIME
line can be entered in the input file. The following table summarizes some of the most used TIME
parameters.
Parameter | Type | Description | Unit | Default |
---|---|---|---|---|
T_BEGIN
|
Real | Starting time for calculation | s | 0. |
T_END
|
Real | Ending time for calculation | s | 1. |
Miscellaneous, MISC
[edit | edit source]MISC
is the namelist group of global miscellaneous input parameters. Many parameters for MISC
exist, some of them are explained later in this manual.
For example:
&MISC SURF_DEFAULT='steel' /
establishes that all bounding surfaces are to be made of steel unless otherwise specified.
Only one MISC
line can be entered in the input file. The following table summarizes some of the most used MISC
parameters.
Parameter | Type | Description | Unit | Default |
---|---|---|---|---|
SURF_DEFAULT
|
String | Default boundary condition | 'INERT'
| |
TMPA
|
Real | Ambient temperature | °C | 20. |
U0 , V0 , W0
|
Real | Initial prevailing velocity field | m/s | 0. |
GVEC(3)
|
Real | Gravity vector | m/s2 | 0.,0.,-9.81 |
RESTART
|
Logical | Restart previous calculation | .FALSE.
|