multy fire rec

Skip to first unread message

Eshchar Yaari

Sep 13, 2022, 1:59:32 PMSep 13
to FDS and Smokeview Discussions
I have a project where I have a truck with a reac of POLYURETHANE and a load of DIESEL fuel on it.
The hrr is 30MW.

i was thinking of two option for this project:
1. One fire box with vent containing the two materials POLYURETHANE and DIESEL where the VOLUME_FRACTION of each is 50.
2. Two separate fire boxes, one POLYURETHANE and the other DIESEL

Attached is my code for the first option. (the second option i couldnt make it run)
I would like an opinion, is my code correct? is there any way to make the second option also?

Randy McDermott

Sep 13, 2022, 2:14:35 PMSep 13
to FDS and Smokeview Discussions
These inputs would take POLYURETHANE_GM27 and assign the properties of nitrogen and then mix it with the DIESEL.

I suggest you take this slowly.  First, get "DIESEL" to work with the correct properties (e.g., heat of combustion, etc.) and make sure you get the correct HRR.

Next, do the same for your POLYURETHANE surrogate.  Note you will have to specify thermodynamic properties, as this is not pre-defined FUEL in FDS.   Again, check that you get the correct HRR for a case with a simple REAC line.

Then, for your option (1), you basically have things right, just mix the SPEC into a new SPEC (but you should use LUMPED_COMPONENT_ONLY=T when defining the DIESEL and POLYURETHANE, search the user guide for LUMPED_COMPONENT_ONLY).

For your option (2), you will need to define your own REAC lines with stoichiometry.  This is discussed in the user guide.  Follow the molar stoichiometric coefficients for the REACs of your individual runs.

You received this message because you are subscribed to the Google Groups "FDS and Smokeview Discussions" group.
To unsubscribe from this group and stop receiving emails from it, send an email to
To view this discussion on the web visit
Reply all
Reply to author
0 new messages