Errors that occur despite having defined species

[MinJoo Lee]

hi. I am trying to analyze the combustion of propane gas in a compartment using the EDC 2step mixing controlled combustion model.

But I keep getting errors like
"ERROR: Problem with REAC 2. Tracked species CARBON DIOXIDE not found. (CHID: 0820_modified)"

Can anyone tell me what the problem is?
I have attached my FDS file.

Thanks.

[Kevin McGrattan]

With the latest source code, I get this error

ERROR: Problem with REAC 1. Tracked species CARBON MONOXIDE not found. (CHID: 0820_modified)

When I add

&SPEC ID='CARBON MONOXIDE' /

the case runs.

 Fire Dynamics Simulator

 Current Date     : August 20, 2023  16:11:09
 Revision         : FDS-6.8.0-567-g3f8c097-master
 Revision Date    : Thu Aug 17 12:16:10 2023 -0400
 Compiler         : ifort version 2021.7.1
 Compilation Date : Aug 17, 2023 15:18:49

[dr_jfloyd]

You may want to look at the User's Guide 13.1.3  With FDS 6.8, you could have gotten the same result without having to use SPEC inputs and having only one REAC:

&REAC FUEL='PROPANE', N_SIMPLE_CHEMISTRY_REACTIONS=2, FUEL_C_TO_CO_FRACTION=1/

[dr_jfloyd]

"Thank you for your answer. However, I have an additional question. I want to implement the EDC two-step mixing controlled combustion model, is it the same as the simple chemistry model?"

There is only one comubstion model in FDS and that is the model described in Chapter 5 of the Technical Reference Guide. Through inputs you can control aspects of the model, for example:

-Change the rate from fast (mixed-is-burnt) to finite rate

-Change the time integration from explicit Euler to a Runge-Kutta method

-Disable mixing by setting the initial unmixed fraction to 0.

Neither the two REAC you originally had nor single simple chemistry input I gave change any of the default parameters for the combustion model.  The simple chemistry input is just saving the time and effort of defining all the species and the reaction stoichiometries.