**1. Introduction**

208 Computational Simulations and Applications

Li, T.; Nishida, K.; Zhang, Y.; Hiroyasu, H. (2007). Effect of split injection on stratified charge

*Research*, Vol. 8, pp. 205-218

formation of direct injection spark ignition engines, *International Journal of Engine* 

Combustion is a natural phenomenon. It happens in forest, automotive engine and gas cooker. In Computational Fluid Dynamics (CFD), the combustion phenomenon complies with a set of partial differential equations. According to the resolution scale, from big to small, the simulation methods in combustion are Reynolds Averaged Navior Stokes method (RANS), Large Eddy Simulation (LES), and Direct Numerical Simulation (DNS). Combustion model research in RANS and LES was, is and will still be a hot topic.

In this chapter, an Algebraic Sub-grid Scale turbulent Combustion Model (ASSCM) for LES is brought forward. Then this model is applied to a partly diffusion jet flame and a premixed flame, after that, the database of the LES simulation results is used to test a RANS turbulent combustion model closure idea. Finally, a DNS by spectral method (Xu et al, 1996) in channel flow is carried on with consideration of buoyancy effects, and the database of the DNS simulation results is used to study RANS and LES turbulent combustion models.
