For spark-ignited engines, a flame front propagates through the unburned mixture according to the local turbulent flame speed of the mixture. The model used for this purpose is the G-equation, as described in Spark Ignition under Models Node. This flame-propagation model may also be used for pilot-spray auto-ignited dual-fuel engines, when the option is turned ON in the Chemistry Solver panel, as described in Chemistry Solver Panel. The local turbulent flame speed used by the G-equation model is calculated based on a correlation to the laminar flame speed, which is a chemical property of the gas mixture. In Ansys Forte, you have three options to describe the laminar flame speed:
The recommended option is the Table Library, which contains pre-built laminar flame speed tables for 54 surrogate fuels that have been calculated from detailed kinetics simulations.
Table Lookup contains pre-built laminar flame speeds that you can assemble externally.
Power-law correlation. The power-law correlation is typically based on curve-fitting of experimental data.