DIRECT NUMERICAL SIMULATION — A TOOL TO STUDY TURBULENT REACTING FLOWS

This paper describes recent progress in the development and application of Direct Numerical Simulation (DNS) for studying turbulent combustion. The role of DNS within numerical simulation techniques is outlined and currently available DNS methods are summarized. The application areas of DNS and its relevance for practical applications are emphasized. In particular, a DNS approach for reactive flows, which was developed by the author and his coworkers is presented in detail. Studies of premixed and non-premixed combustion performed with this method are reported upon. Investigations of premixed flames by DNS presented in this paper address the issues of flame–vortex interactions, flame dynamics in homogeneous isotropic turbulence, flame ignition and flame–wall interactions. Simplified as well as detailed reaction mechanisms were considered in these simulations. Most of these studies were performed in the framework of flamelet modelling and therefore the impact of DNS on this research activity is emphasized. While simulations of premixed combustion are discussed in more detail, a short overview on investigations of non-premixed combustion is also given. The DNS of the diffusion flames presented here focus on combustion in mixing layers, e.g., auto-ignition processes and the application area of the laminar flamelet assumption. A brief discussion of open issues and ongoing work concludes this review.