Analysis of turbulent transport and mixing in transitional Rayleigh–Taylor unstable flow using direct numerical simulation data
Data from a 1152X760X1280 direct numerical simulation (DNS) of a transitional RayleighTaylor mixing layer modeled after a small Atwood number water channel experiment is used to comprehensively investigate the structure of mean and turbulent transport and mixing. The simulation had physical parameters and initial conditions approximating those in the experiment. The budgets of the mean vertical momentum, heavyfluid mass fraction, turbulent kinetic energy, turbulent kinetic energy dissipation rate, heavyfluid mass fraction variance, and heavyfluid mass fraction variance dissipation rate equations are constructed using Reynolds averaging applied to the DNS data. The relative importance of mean and turbulent production, turbulent dissipation and destruction, and turbulent transport are investigated as a function of Reynolds number and across the mixing layer to provide insight into the flow dynamics not presently available from experiments. The analysis of the budgets supports the assumption for small Atwood number, Rayleigh/Taylor driven flows that the principal transport mechanisms are buoyancy production, turbulent production, turbulent dissipation, and turbulent diffusion (shear and mean field production are negligible). As the Reynolds number increases, the turbulent production in the turbulent kinetic energy dissipation rate equation becomes the dominant production term, while the buoyancy production plateaus. Distinctions between momentum and scalar transport aremore »
 Authors:

^{[1]};
^{[2]}
 Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
 Texas A & M Univ., College Station, TX (United States)
 Publication Date:
 OSTI Identifier:
 1076443
 Grant/Contract Number:
 AC5207NA27344
 Type:
 Accepted Manuscript
 Journal Name:
 Physics of Fluids (1994)
 Additional Journal Information:
 Journal Name: Physics of Fluids (1994); Journal Volume: 22; Journal Issue: 10; Journal ID: ISSN 10706631
 Publisher:
 American Institute of Physics
 Research Org:
 Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
 Sponsoring Org:
 USDOE Office of Science (SC)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS turbulent flow; turbulent transport processes; turbulent mixing layers; Reynolds stress modeling; flow instabilities