Dependence of convective boundary mixing on boundary properties and turbulence strength

A. Cristini, R. Hirschi, C. Meakin, W David Arnett, C. Georgy, I. Walkington

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Convective boundary mixing is one of the major uncertainties in stellar evolution. In order to study its dependence on boundary properties and turbulence strength in a controlled way, we computed a series of 3D hydrodynamical simulations of stellar convection during carbon burning with a varying boosting factor of the driving luminosity. Our 3D implicit large eddy simulations were computed with the prompi code. We performed a mean field analysis of the simulations within the Reynolds-averaged Navier-Stokes framework. Both the vertical rms velocity within the convective region and the bulk Richardson number of the boundaries are found to scale with the driving luminosity as expected from theory: v ' L 1/3 and Ri B ' L '2/3, respectively. The positions of the convective boundaries were estimated through the composition profiles across them, and the strength of convective boundary mixing was determined by analysing the boundaries within the framework of the entrainment law. We find that the entrainment is approximately inversely proportional to the bulk Richardson number, Ri B (propto textrmRi-textrmB -alpha , alpha sim 0.75). Although the entrainment law does not encompass all the processes occurring at boundaries, our results support the use of the entrainment law to describe convective boundary mixing in 1D models, at least for the advanced phases. The next steps and challenges ahead are also discussed.

Original languageEnglish (US)
Pages (from-to)4645-4664
Number of pages20
JournalMonthly Notices of the Royal Astronomical Society
Volume484
Issue number4
DOIs
StatePublished - Apr 21 2019

Fingerprint

turbulence
entrainment
Richardson number
stellar convection
luminosity
stellar evolution
large eddy simulation
simulation
convection
carbon
profiles

Keywords

  • convection
  • hydrodynamics
  • ISM: evolution

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Dependence of convective boundary mixing on boundary properties and turbulence strength. / Cristini, A.; Hirschi, R.; Meakin, C.; Arnett, W David; Georgy, C.; Walkington, I.

In: Monthly Notices of the Royal Astronomical Society, Vol. 484, No. 4, 21.04.2019, p. 4645-4664.

Research output: Contribution to journalArticle

Cristini, A. ; Hirschi, R. ; Meakin, C. ; Arnett, W David ; Georgy, C. ; Walkington, I. / Dependence of convective boundary mixing on boundary properties and turbulence strength. In: Monthly Notices of the Royal Astronomical Society. 2019 ; Vol. 484, No. 4. pp. 4645-4664.
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