## Chapter 7: Combustion Theory

This chapter covers the implementation of the combustion models in the CFX-Solver and extends the ideas covered in Multicomponent Flow. You should be familiar with the multicomponent flow chapter before reading this section.

This chapter describes:

- Transport Equations
- Chemical Reaction Rate
- Fluid Time Scale for Extinction Model
- The Eddy Dissipation Model
- The Finite Rate Chemistry Model
- The Combined Eddy Dissipation/Finite Rate Chemistry Model
- Combustion Source Term Linearization
- The Flamelet Model
- Burning Velocity Model (Premixed or Partially Premixed)
- Burning Velocity Model (BVM)
- Laminar Burning Velocity
- Turbulent Burning Velocity
- Extended Coherent Flame Model (ECFM)
- Residual Material Model
- Spark Ignition Model
- Autoignition Model
- Phasic Combustion
- NO Formation Model
- Chemistry Postprocessing
- Soot Model

The following sections outline the basis of the implementation of combustion modeling in CFX. First, the transport equations for energy and the components are revisited, then the chemical reaction rate computation is described, and finally, the computation of the rate of progress of a chemical reaction is explained in the context of the Eddy Dissipation and Finite Rate Chemistry Models. Extinction is modeled by setting the reaction rate locally to zero.

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