The conditions requested to obtain a successful autoignition in a turbulent gas mixture have been mostly investigated in the past through experiments or highly simplified models. A quantitative numerical investigation requires an excellent description of the turbulent flow coupled to an accurate representation of all relevant chemical, diffusive and thermodynamic processes. This leads to extremely high requirements in terms of computing time, preventing any practical use for safety analysis up to now. There is therefore an obvious need to pursue such investigations, including the development of suitable reduced models. This is realized in the present project based on Direct Numerical Simulation with exact physicochemical models. In order to cover a wide range of safety-relevant auto-ignition, different reaction mixtures (H₂/air and C₂H₄/air) and different flame structures will be investigated (homogenous, spherical, jet, etc...).

Our team will work with a multi-dimensional in-house DNS code (DINOSOARS) during the current phase of the project. DINOSOARS (DIrect Numerical, high-Order Simulation and On-the-fly Analysis of Reacting flows and Sprays) is a new Fortran-2003 code which is developed in our group since the beginning of 2013. DINOSOARS is three dimensional, uses a 6th order finite difference spatial discretization and low Mach number solver for reacting and multi-phase turbulent flows. The code is parallelized in two dimensions using 2DECOMP&FFT library on top of standard MPI and FFTW. Also, 3rd and 4th order Runge-Kutta implicit time integration schemes are used for stiff chemistry part in the governing equations, in order to increase the integration time step.