Two-equation and multi-fluid turbulence models for Rayleigh–Taylor mixing

Ioannis Kokkinakis, D. Drikakis, D. L. Youngs, R. J. R. Williams

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

This paper presents a new, improved version of the K–L model, as well as a detailed investigation of K–L and multi-fluid models with reference to high-resolution implicit large eddy simulations of compressible Rayleigh–Taylor mixing. The accuracy of the models is examined for different interface pressures and specific heat ratios for Rayleigh–Taylor flows at initial density ratios 3:1 and 20:1. It is shown that the original version of the K–L model requires modifications in order to provide comparable results to the multi-fluid model. The modifications concern the addition of an enthalpy diffusion term to the energy equation; the formulation of the turbulent kinetic energy (source) term in the K equation; and the calculation of the local Atwood number. The proposed modifications significantly improve the results of the K–L model, which are found in good agreement with the multi-fluid model and implicit large eddy simulations with respect to the self-similar mixing width; peak turbulent kinetic energy growth rate, as well as volume fraction and turbulent kinetic energy profiles. However, a key advantage of the two-fluid model is that it can represent the degree of molecular mixing in a direct way, by transferring mass between the two phases. The limitations of the single-fluid K–L model as well as the merits of more advanced Reynolds-averaged Navier–Stokes models are also discussed throughout the paper.
LanguageEnglish
Pages233-250
Number of pages18
JournalInternational Journal of Heat and Fluid Flow
Volume56
Early online date28 Aug 2015
DOIs
Publication statusPublished - Dec 2015

Fingerprint

turbulence models
Turbulence models
Fluids
fluids
Kinetic energy
kinetic energy
large eddy simulation
Large eddy simulation
two fluid models
energy sources
Specific heat
Enthalpy
Volume fraction
enthalpy
specific heat
formulations
heat
high resolution
profiles

Keywords

  • compressible turbulent mixing
  • Rayleigh–Taylor
  • engineering turbulence modeling

Cite this

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title = "Two-equation and multi-fluid turbulence models for Rayleigh–Taylor mixing",
abstract = "This paper presents a new, improved version of the K–L model, as well as a detailed investigation of K–L and multi-fluid models with reference to high-resolution implicit large eddy simulations of compressible Rayleigh–Taylor mixing. The accuracy of the models is examined for different interface pressures and specific heat ratios for Rayleigh–Taylor flows at initial density ratios 3:1 and 20:1. It is shown that the original version of the K–L model requires modifications in order to provide comparable results to the multi-fluid model. The modifications concern the addition of an enthalpy diffusion term to the energy equation; the formulation of the turbulent kinetic energy (source) term in the K equation; and the calculation of the local Atwood number. The proposed modifications significantly improve the results of the K–L model, which are found in good agreement with the multi-fluid model and implicit large eddy simulations with respect to the self-similar mixing width; peak turbulent kinetic energy growth rate, as well as volume fraction and turbulent kinetic energy profiles. However, a key advantage of the two-fluid model is that it can represent the degree of molecular mixing in a direct way, by transferring mass between the two phases. The limitations of the single-fluid K–L model as well as the merits of more advanced Reynolds-averaged Navier–Stokes models are also discussed throughout the paper.",
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author = "Ioannis Kokkinakis and D. Drikakis and Youngs, {D. L.} and Williams, {R. J. R.}",
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Two-equation and multi-fluid turbulence models for Rayleigh–Taylor mixing. / Kokkinakis, Ioannis; Drikakis, D.; Youngs, D. L.; Williams, R. J. R.

In: International Journal of Heat and Fluid Flow, Vol. 56, 12.2015, p. 233-250.

Research output: Contribution to journalArticle

TY - JOUR

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AU - Drikakis, D.

AU - Youngs, D. L.

AU - Williams, R. J. R.

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AB - This paper presents a new, improved version of the K–L model, as well as a detailed investigation of K–L and multi-fluid models with reference to high-resolution implicit large eddy simulations of compressible Rayleigh–Taylor mixing. The accuracy of the models is examined for different interface pressures and specific heat ratios for Rayleigh–Taylor flows at initial density ratios 3:1 and 20:1. It is shown that the original version of the K–L model requires modifications in order to provide comparable results to the multi-fluid model. The modifications concern the addition of an enthalpy diffusion term to the energy equation; the formulation of the turbulent kinetic energy (source) term in the K equation; and the calculation of the local Atwood number. The proposed modifications significantly improve the results of the K–L model, which are found in good agreement with the multi-fluid model and implicit large eddy simulations with respect to the self-similar mixing width; peak turbulent kinetic energy growth rate, as well as volume fraction and turbulent kinetic energy profiles. However, a key advantage of the two-fluid model is that it can represent the degree of molecular mixing in a direct way, by transferring mass between the two phases. The limitations of the single-fluid K–L model as well as the merits of more advanced Reynolds-averaged Navier–Stokes models are also discussed throughout the paper.

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