Naming the Input File
Each scenario in the Fenix+ 3 project has its unique identifier – an 8-character alfanumeric sequence. Only letter characters can be used. This identifier is used as the name for the FDS input file (e.g., “0de3621b.fds”).
Parameter Group Format
Each parameter group in the input file begins with an “&” and ends with a “/”. Anything outside these symbols is considered a comment and is ignored by FDS.
Examples of parameter groups:
&VENT XB=4,6,2,3,0.5,0.5 SURF_ID='1' SPREAD_RATE=0.0068 XYZ=5.125,2.625,0.5 CTRL_ID='2'/
&SURF ID='1' FYI='Fire source 1' HRRPUA=2350.296 COLOR='RED'/
Immediately following the “&” symbol is the name of the parameter group. The name is followed by a list of parameters and their values, formatted as =. Parameters can be separated by commas or spaces, with Fenix+ 3 using spaces for separation.
Parameters can be on multiple lines. Fenix+ 3 puts all parameters in one line.
If FDS provides a default value for a parameter that matches the required scenario value, that parameter can be excluded from the input file.
Some parameter groups include an “ID” parameter, set uniquely for each group with an index. This index is used to reference the parameter group. For example, an OBST parameter group might reference a SURF parameter group describing the properties of the surface covering the OBST. Similarly, the SURF group might refer to a MATL group detailing the material properties:
&MATL **ID='3'** CONDUCTIVITY=1 DENSITY=1000 SPECIFIC_HEAT=1/
&SURF **ID='4'** THICKNESS=0.25 RGB=128,128,128 **MATL_ID='3'**/
&OBST XB=2.75,3,1.75,2,0,3.1 **SURF_ID='4'** RGB=128,128,128/
Input File Structure
The input file begins with the HEAD parameter group:
&HEAD CHID='0de3621b' TITLE='New project: Scenario 2' FYI='File generated by Fenix+ 3 Ultimate 3.0.6 for FDS6'/
CHID - a string (maximum 30 characters) used to name all files resulting from the FDS operation. Fenix+ 3 uses the scenario identifier for CHID, which corresponds to the input file name.
TITLE - a description of the scenario (maximum 30 characters), which does not influence the simulation results. If the transliterated scenario name exceeds 30 characters, TITLE is composed of the start and end of the name to meet the character limit.
FYI an additional note or comment, not affecting simulation results. In the FYI parameter, Fenix+ 3 indicates the version used to generate the file and the FDS version it supports.
The input file concludes with the TAIL parameter group, which contains no parameters:
&TAIL /
Between the HEAD and TAIL groups, all other groups define the fire development scenario and simulation parameters for FDS.
Currently, Fenix+ 3 uses the following groups for generating the input file:
DUMP, TIME, MISC, MESH, VENT, SURF, OBST, REAC, DEVC, SLCF, RAMP, SPEC, BNDF, ZONE, INIT
Not all groups are necessarily present in each input file. The specific set of groups that are used depends on the scenario and simulation parameters specified by the user in the Fenix+ 3 scenario.
The conversion of all Fenix+ 3 scenario components into the corresponding parameter groups in the FDS input file is described in other sections of this document.