Convective overshooting and penetration in a Boussinesq spherical shell

Korre, Lydia; Garaud, Pascale; Brummell, Nicholas H.

doi:10.1093/mnras/stz047

Cited by 43 publications

(67 citation statements)

References 65 publications

(126 reference statements)

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“…In reality, both processes occur and influence each other (e.g. Brun et al 2017;Korre, Garaud & Brummell 2019) but it is still an open question how convection and rotation interact with each other. Gabriel et al (2014) discussed the important issue of discontinuities at convective boundaries and how to choose the 'right' convective boundary location in the framework of the MLT.…”

Section: Discussionmentioning

confidence: 99%

Relative importance of convective uncertainties in massive stars

Kaiser

Hirschi

Arnett

et al. 2020

Monthly Notices of the Royal Astronomical Society

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ABSTRACT In this work, we investigate the impact of uncertainties due to convective boundary mixing (CBM), commonly called ‘overshoot’, namely the boundary location and the amount of mixing at the convective boundary, on stellar structure and evolution. For this we calculated two grids of stellar evolution models with the MESA code, each with the Ledoux and the Schwarzschild boundary criterion, and vary the amount of CBM. We calculate each grid with the initial masses of 15, 20, and $25\, \rm {M}_\odot$. We present the stellar structure of the models during the hydrogen and helium burning phases. In the latter, we examine the impact on the nucleosynthesis. We find a broadening of the main sequence with more CBM, which is more in agreement with observations. Furthermore, during the core hydrogen burning phase there is a convergence of the convective boundary location due to CBM. The uncertainties of the intermediate convective zone remove this convergence. The behaviour of this convective zone strongly affects the surface evolution of the model, i.e. how fast it evolves redwards. The amount of CBM impacts the size of the convective cores and the nucleosynthesis, e.g. the 12C to 16O ratio and the weak s-process. Lastly, we determine the uncertainty that the range of parameter values investigated introduces and we find differences of up to $70{{\ \rm per\ cent}}$ for the core masses and the total mass of the star.

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Section: Discussionmentioning

confidence: 99%

Relative importance of convective uncertainties in massive stars

Kaiser

Hirschi

Arnett

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…Instead, they used the statistical probability density function of extreme events to make the assessment. As mentioned in Korre et al (2019), the correlation coefficients of vertical velocity tend to capture the extreme events. Thus we believe that our work shares some similarities with the work of Pratt et al (2017).…”

Section: The Measurement Of Overshooting Distancesmentioning

confidence: 89%

“…In recent years, much attention has been paid to the numerical simulations of the turbulent convection and overshooting (Brummell et al 2002;Hotta 2017;Brun et al 2017;Käpylä et al 2017;Käpylä 2019;Korre et al 2019). Most of them studied the downward overshooting below a convection zone.…”

Section: Introductionmentioning

confidence: 99%

Upward Overshooting in Turbulent Compressible Convection. III. Calibrate Parameters for One-dimensional Reynolds Stress Model

Cai

2020

ApJ

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In this paper, we calibrate the coefficients for the one-dimensional Reynolds stress model with the data generated from the three-dimensional numerical simulations of upward overshooting in turbulent compressible convection. It has been found that the calibrated convective and isotropic coefficients are almost the same as those calibrated in the pure convection zone. However, the calibrated diffusive coefficients differ significantly from those calibrated in the pure convection zone. We suspect that the diffusive effect induced by the boundary is stronger than by the adjacent stable zone. We have checked the validity of the downgradient approximation. We find that the prediction of the downgradient approximation on the third-order moments is unsatisfactory. However, the prediction on their derivatives is much better. It explains why the performance of the Reynolds stress model is reasonable in application to the real stars. With the calibrated coefficients, we have solved the full set of nonlocal turbulent equations on Reynolds stress model. We find that the Reynolds stress model has successfully produced the thermal adjustment layer and turbulent dissipation layer, which were identified in the three-dimensional numerical simulations. We suggest to use the inflection point of the auto-correlation of temperature perturbation and the Péclet number as the indicators on measuring the extents of the thermal adjustment layer and turbulent dissipation layer, respectively. This result may offer a practical guidance on the application of the Reynolds stress model in 1D stellar structure and evolution models.

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“…We find that the results have no big difference (see the appendix for more details). The abrupt change of ∇ is also presented in the simulation results of the downward overshooting in Korre et al (2019)…”

Section: The Effect Of Relative Stability Smentioning

confidence: 93%

Upward Overshooting in Turbulent Compressible Convection. I. Effects of the Relative Stability Parameter, the Prandtl Number, and the Péclet Number

Cai

2020

ApJ

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In this paper, we investigate the upward overshooting by three-dimensional numerical simulations. We find that the above convectively stable zone can be partitioned into three layers: the thermal adjustment layer (mixing both entropy and material), the turbulent dissipation layer (mixing material but not entropy), and the thermal dissipation layer (mixing neither entropy nor material). The turbulent dissipation layer is separated from the thermal adjustment layer and the thermal dissipation layer by the first and second zero points of the vertical velocity correlation. The simulation results are in good agreement with the prediction of the one-dimensional turbulent Reynolds stress model. First, the layer structure is similar. Second, the upper boundary of the thermal adjustment layer is close to the peak of the magnitude of the temperature perturbation. Third, the Péclet number at the upper boundary of the turbulent dissipation layer is close to 1. In addition, we have studied the scalings of the overshooting distance on the relative stability parameter S, the Prandtl number Pr, and the Péclet number Pe. The scaling on S is not unique. The trend is that the overshooting distance decreases with S. Fitting on Pr shows that the overshooting distance increases with Pr. Fitting on Pe shows that the overshooting distance decreases with Pe. Finally, we calculate the ratio of the thickness of the turbulent dissipation layer to that of the thermal adjustment layer. The ratio remains almost constant, with an approximate value of 2.4.

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Convective overshooting and penetration in a Boussinesq spherical shell

Cited by 43 publications

References 65 publications

Relative importance of convective uncertainties in massive stars

Relative importance of convective uncertainties in massive stars

Upward Overshooting in Turbulent Compressible Convection. III. Calibrate Parameters for One-dimensional Reynolds Stress Model

Upward Overshooting in Turbulent Compressible Convection. I. Effects of the Relative Stability Parameter, the Prandtl Number, and the Péclet Number

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