Reynolds Number Effects on Scalar Dissipation Rate Transport and Its Modeling in Turbulent Premixed Combustion

Abstract

The effects of turbulent Reynolds number, Re _t , on the transport of scalar dissipation rate of reaction progress variable in the context of Reynolds averaged Navier–Stokes simulations have been analyzed using three-dimensional simplified chemistry-based direct numerical simulation (DNS) data of freely propagating turbulent premixed flames with different values of Re _t . Scaling arguments have been used to explain the effects of Re _t on the turbulent transport, scalar–turbulence interaction, and the combined reaction and molecular dissipation terms. Suitable modifications to the models for these terms have been proposed to account for Re _t effects, and the model parameters include explicit Re _t dependence. These expressions approach expected asymptotic limits for large values of Re _t . However, turbulent Reynolds number Re _t does not seem to have any major effects on the modeling of the term arising from density variation.

Keywords:

• Direct numerical simulations
• Reynolds averaged Navier–Stokes simulation
• Scalar dissipation rate
• Transport equation based closure
• Turbulent Reynolds number

ACKNOWLEDGMENT

The authors are grateful to the Engineering and Physical Sciences Research Council (EPSRC), UK, for financial support.