Detailed autoignition kinetics is used for ignition. Here we briefly describe the autoignition transition criteria [85] from ignition kernel to G-equation. Ansys Forte checks two criteria: critical temperature and size of the ignition kernel.

After the ignition kernel is formed, the flame propagation model is activated. Computational cells with temperatures greater than the critical temperature become ignition sites. For each of these cells, if the ignition kernel radius is greater than the TLS (turbulent length scale), a G (x, t) = 0 surface is initialized. This surface divides the areas where the gas temperature is lower or higher than the critical temperature. The area inside the surface is the area of ignition.