Direct Numerical Simulation of High-Pressure Multispecies Turbulent Mixing in the Cold Ignition Regime

Abstract

A model is proposed for describing mixing of several species under high pressure conditions that relies on a previously proposed model based on governing equations for multispecies mixing that has so far only been exercised for two-species mixing. For the two-species mixing simulations, transport properties were computed from correlated Schmidt (Sc) and Prandtl (Pr) numbers, accurately calculated as functions of the thermodynamic variables, and from a specified Reynolds number value from which an adjusted viscosity value was calculated so as to enable Direct Numerical Simulation (DNS). One of the novelties of the present study is the modeling and computation of multispecies mixing based on a full mass-diffusion matrix, a full thermal-diffusion-factor matrix necessary to include Soret and Dufour effects, and thermal conductivity computed for the species mixture. The scaling of the viscosity necessary for conducting DNS induces a scaling of the other transport properties that respects the accurate values of the Sc numbers and of the Pr number. Computations are performed with five species in the configuration of a temporal mixing layer and the effect of transport properties on species mixing and layer development are analyzed and discussed.

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