During the initial analysis of a combustor, the highest values of temperature and outgoing heat flux are likely to be of primary concern. For this purpose, a single-step Eddy Dissipation reaction can be used. Such a reaction is likely to overpredict the temperature, and will not predict emissions correctly, but can provide a conservative indicator of the expected temperature levels.

Other reaction steps might then be added to the simulation to account for the formation of combustion byproducts. Each reaction step has its own separate time scale. As a result, convergence can become very difficult when a multi-step reaction contains more than about 5 steps.