Dependence of Convective Boundary Mixing on Boundary Properties and Turbulence Strength. (arXiv:1901.10531v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Cristini_A/0/1/0/all/0/1">A. Cristini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hirschi_R/0/1/0/all/0/1">R. Hirschi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Meakin_C/0/1/0/all/0/1">C. Meakin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Arnett_D/0/1/0/all/0/1">D. Arnett</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Georgy_C/0/1/0/all/0/1">C. Georgy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Walkington_I/0/1/0/all/0/1">I. Walkington</a>
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. 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. 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.
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. 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. 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.
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