Models for Reactive Flows

In this chapter, some techniques are presented for obtaining reduced kinetic mechanisms as the Direct Relation Graph (DRG) the sensitivity analysis based on the eigenvalues and eigenvectors of the Jacobian matrix of the chemical system, and techniques such as Intrinsic Low Dimensional manifolds (ILDM), Reaction Diffusion manifolds (REDIM), and flamelet. For premixed flames, laminar burning velocity and the basic equations are obtained, and the length and time scales are discussed. In order to represent the flame front, the G equation is discussed. For diffusion flames, flamelet equations are presented with the introduction of the probability density function and the scalar dissipation rate. The Burke-Schumann solution and an analytical solution for jet diffusion flames and for plumes are also illustrated. Then, models are presented for reactive flows in porous media. Initially, we discuss the model of Darcy and appropriate equations for precipitation and dissociation of minerals without combustion. Finally, the equations are presented for combustion in porous media and a discussion about ion precipitation is made.