Laminar flamelet decomposition for conditional source-term estimation

A new decomposition approach to conditional source- term estimation (CSE) is proposed and discussed. The new approach is tested in the a priori sense using direct numerical simulations (DNS). It is found that - where CSE had previously been found to provide closure for chemical source- terms with arbitrary chemistry in the large eddy simulation paradigm - it can provide this closure in the Reynolds averaged Navier - Stokes paradigm as well. Using the proposed decomposition improves the predictions of CSE considerably. Only the assumptions that gradients in conditional averages are small and that the probability density function of mixture fraction can be adequately approximated using a presumed functional form are needed. The computational cost of the new laminar flamelet decomposition approach to CSE is also substantially lower than that of the original approach. (C) 2003 American Institute of Physics.