Sample chemistry set files are located in the system data folder installed with Ansys Forte. These files can be accessed directly by browsing to the .cks file from the Import Chemistry   button on the Chemistry Set tab (see Chemistry). A description of each of the provided chemistry sets is provided in this section, including reference to the source of the chemistry mechanism, the reduction method used and the expected applicable range of conditions.

While these mechanisms can serve as a starting point in exploring detailed fuel kinetics with Ansys Forte, they should not be applied outside of the range of applicability suggested. ANSYS builds such mechanisms from a large database of full mechanisms for over 60 model-fuel components and different surrogate-fuel blends. These full mechanisms have been carefully validated over a wide range of engine-relevant conditions, under work sponsored by the Model Fuels Consortium [15]. The Ansys Model Fuel Library (MFL) Manual (available in the Ansys Chemkin installation) includes the mechanism validation plots. Skeletal mechanisms for use in Ansys Forte are generated by setting up an Ansys Chemkin project that represents the specific range of conditions of interest and for a specific model-fuel blend and then applying a variety of automated mechanism-reduction methods to achieve specific targets within specific error tolerances. In this way, ANSYS can provide services or additional software tools to assist in the tailoring of mechanisms to a specific application. The mechanisms are reduced using the targeted automated mechanism reduction facility in Ansys Chemkin Reaction Workbench. Several methods, including Directed Relation Graph (DRG), DRG with Error Propagation (DRGEP), DRG with Path Flux Analysis (DRGPFA), sensitivity analysis, and automatic isomer, are used in an iterative fashion to create the reduced mechanisms from the full mechanisms in the Ansys MFL.

For the mechanisms included with Ansys Forte, review the application range and the targets / error tolerances used in the reduction to make sure they are appropriate for your application. There are two types of mechanisms included with Forte. As shown in Table 1: Summary of the Ansys MFL-based pre-reduced reaction mechanisms included with Forte, 1-component mechanisms are provided for natural gas, gasoline, and diesel. Note that for diesel, it is listed as n-heptane + methane that is also applicable for dual fuel engines. These 1-component mechanisms are smaller in size and provide a quick and reliable engine simulation. They can be used to perform initial calibrations of the baseline case. They also can be used with an empirical acetylene-based soot model. For more accurate results, 2- or 3-component surrogates for gasoline and diesel should be used. For gasoline, we provide the mechanism for TPRF fuels containing toluene/iso-octane/n-heptane. The mechanism contains a chemistry of ethanol for modeling gasoline-ethanol blends. Diesel fuel can be modeled using 2 components: n-decane/ 1-methyl naphthalene. Two versions of soot models are included for the multi-component mechanisms: a pseudo-gas soot model, and a detailed soot-surface mechanism. The pseudo-gas soot model is a multi-step model that uses benzene-based precursors for soot formation. It provides soot mass and treats "soot" as a gas-phase species. For the most accurate prediction of soot mass and size distribution, use a detailed soot-surface mechanism. It uses heavier PAH species, such as coronene, for the nucleation and growth steps. Soot is tracked using the Particle Tracking model in Ansys Forte.

The mechanisms listed in Table 1: Summary of the Ansys MFL-based pre-reduced reaction mechanisms included with Forte are specifically created for the surrogates and their compositions described in the following sections. The same multi-component mechanisms can be used for a slightly different composition. For a brief description on creating a surrogate to match a specific test fuel, refer to Creating a Surrogate for a Specific Test Fuel. If a higher level of accuracy in fuel models is required to capture fuel effects and emissions, more complex surrogates with additional components may be required. For additional multi-component surrogates and their mechanisms, refer to the Ansys Model Fuel Library Manual.