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Abstract
The influence of turbulent Reynolds number (Re t ) on the statistical behavior and modeling of turbulent scalar flux (TSF) has been analyzed using a direct numerical simulation database of freely propagating turbulent premixed flames. A range of different values of Re t is considered in which the Damköhler and Karlovitz numbers are modified independent of each other to bring about the variation of Re t . It has been found that the qualitative behavior of the various terms of the TSF transport equation does not change by the variation of Re t , but their relative contributions to the transport of TSF are affected to some extent. The effects of Re t on the modeling of the TSF using both algebraic and transport equation-based closures are addressed in detail. It is demonstrated that model parameters for an existing algebraic model, and the models for turbulent transport, pressure gradient and the reaction rate terms in the TSF transport equation, all exhibit Re t dependence for small values of Re t but all assume asymptotic values for Re t ≥ 50. By contrast, the model parameters for the combined molecular diffusion term are found to be insensitive to the variation of turbulent Re t . Existing models for algebraic and transport equation-based closures of TSF have been modified to account for the observed Re t dependence.
Notes
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