A multispecies turbulence model for the mixing and de-mixing of miscible fluids

Abstract

A de-mix capable model for turbulence in compressible, variable density flows is proposed. The model is based on the Besnard-Harlow-Rauenzahn (BHR) family of models (Besnard D, Harlow F, Rauenzahn R, et al. Turbulence transport equations for variable-density turbulence and their relationship to two-field models. NM (United States): Los Alamos National Laboratory; 1992 (Technical Report LA-12303-MS), but is extended to track the evolution of the turbulent fluxes and fluctuations in the material mass fractions for each species present. The new evolution equations are introduced without requiring additional closures or new empirically tuned coefficients relative to previous BHR models, and are shown to improve the model’s ability to reproduce the behaviour of simulations containing mixing layers that are constrained by a stabilising force. The model is tested in a range of canonical flows including Rayleigh-Taylor driven, shock driven, and shear driven turbulence, and is shown to produce reasonable agreement with simulations and experiments in these scenarios.

KEYWORDS:

• Turbulent mixing
• Reynolds averaged navier-stokes
• turbulence modelling: Reynolds averaged
• supersonic turbulent flows

Acknowledgements

We would like to acknowledge the Eulerian Applications Project (EAP) for their aid in the implementation and support of the mix modelling capabilities in the xRage hydrocode.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the US Department of Energy through the Los Alamos National Laboratory. Los Alamos National Laboratory is operated by Triad National Security, LLC, for the National Nuclear Security Administration of U.S. Department of Energy (Contract No. 89233218CNA000001). This work was partially funded by the Mix and Burn project under the Physics and Engineering Models program of the DOE Advanced Simulation and Computing program.