(312i) Multi-Environment Conditional Pdf Model Validation Study Using Reacting Flow Dns Conference: AIChE Annual MeetingYear: 2006Proceeding: 2006 AIChE Annual MeetingGroup: Engineering Sciences and FundamentalsSession: Turbulent Flows Time: Tuesday, November 14, 2006 - 5:15pm-5:30pm Authors: Smith, S. T., Iowa State University Fox, R. O., Iowa State University Chen, J. H., Combustion Research Facility, Sandia CA Hawkes, E. R., Combustion Research Facility, Sandia CA A validation study has been preformed for the Multi-Environment Conditional Probability-Density Function (MECPDF) model for turbulent combustion under conditions of local extinction and re-ignition. The study investigated issues regarding complex combustion chemistry, variable density and conditional-dissipation terms that are modeled in the MECPDF framework. The data used for the analysis included results of direct numerical simulations (DNS) of temporally-evolving plane jet flames with detailed CO/H2 kinetics as described elsewhere (E. R. Hawkes et al., Proc. of the Combust. Inst., 31, in press.) The three-dimensional turbulent reacting flow simulations included up to 500 million grid points and Reynolds numbers up to 9,000. With these data, a priori errors in the quadrature and physical approximations required for the MECPDF model are quantified. Trends in Reynolds number will be presented. The order of conditional moments required for accurate description of the extinction and re-ignition phenomena will be discussed.