12.1.15. Chemical Reactions

See Setting up chemical reaction cases for information on using these keywords.

12.1.15.1. STIFF_CHEMISTRY

Data Type: LOGICAL

Flag to use stiff chemistry solver (Direct integration).

12.1.15.2. STIFF_CHEM_MAX_STEPS

Data Type: INTEGER

Maximum number of internal steps ODEPACK may use to integrate over the time interval. Leaving this value unspecified defaults to 500,000 steps. The stiff solver reports the number of cells that exceed the number of steps as ‘incomplete’.

12.1.15.3. STIFF_CHEM_ABS_TOL

Data Type: DOUBLE PRECISION

Stiff chemistry solver absolute tolerance. Applies to all equations.

12.1.15.4. STIFF_CHEM_REL_TOL

Data Type: DOUBLE PRECISION

Stiff chemistry solver relative tolerance. Applies to all equations.

12.1.15.5. STIFF_CHEM_MIN_RATE

Data Type: DOUBLE PRECISION

Stiff chemistry minimum fluid reaction rate. If all fluid reaction rates are below this threshold, a cell is said to be non-reactive and no ODE is set for this cell.

12.1.15.6. STIFF_CHEM_MIN_RATE_DPM

Data Type: DOUBLE PRECISION

Stiff chemistry minimum DPM (Discrete phase model) reaction rate. If all DPM reaction

rates are below this threshold, a particle/parcel is said to be non-reactive and no ODE is set for this particle/parcel.

12.1.15.7. STIFF_CHEM_MIN_SPECIES

Data Type: DOUBLE PRECISION

Stiff chemistry minimum species mass fraction. Reactions are switched off when reactants fall below this threshold.

12.1.15.8. USE_RRATES

Data Type: LOGICAL

Flag to use legacy chemical reaction UDFs.

12.1.15.9. SPECIES_NAME(PHASE)

Data Type: CHARACTER

• \(0 \le Phase \le 10\)

Names of gas and solids phase species as it appears in the materials database. The first NMAX(0) are the names of gas species. The next NMAX(1) are the names of solids phase-1 species, etc.

12.1.15.10. NMAX(PHASE)

Data Type: INTEGER

• \(0 \le Phase \le 10\)

Number of species in phase m. Note that the gas phase is indicated as m=0.