On the role of mass diffusion and fluid dynamics in the dissipation of chunk mix

Technical Report · Mon Mar 01 04:00:00 EST 1999

DOI:https://doi.org/10.2172/8402· OSTI ID:8402

Cloutman, L D ^[1]

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1. LLNL

When numerically simulating multicomponent turbulent flows, subgrid-scale diffusion of chemical species requires closure. This mixing of chemical species at the molecular level dissipates concentration uctuations, which limits possible demixing and affects other pro- cesses such as energy transport and reaction rates at the subgrid level. We discuss some of the physical processes that reduce small chunks of a heavy material in a light gas or plasma to a mixture at the atomic level. Preliminary direct numerical simulations of these processes are presented using the dissipation of small spheres of heavy gas in a light gas as an archetypal process in turbulent micromixing in multicomponent ows, including classical uid instabilities and shock ejecta. We use a detailed approach for the diffusion process, directly solving the Stefan-Maxwell equations for the mass fluxes. We discuss the dissipa- tion of a 24µm sphere of xenon in helium in three different flow regimes, and we present suggestions for future work intended as input to improved subgrid-scale turbulence models.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA
• Sponsoring Organization: USDOE Office of Defense Programs (DP)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 8402
• Report Number(s): UCRL-ID-133412; DP0101031; ON: DE00008402
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Diffusion
Fluid Mechanics
Gases
Mixing
Plasma