Comparison of 2D and 3D compressible convection in a pre-main sequence star

Abstract

Context. A 1D description of stellar dynamics is at the basis of stellar evolution modeling. Designed to investigate open problems in stellar evolution, the MUltidimensional Stellar Implicit Code expands a realistic 1D profile of a star’s internal structure to examine the interior dynamics of a specific star through either 2D or 3D hydrodynamic simulations. Aims. Extending our recent studies of 2D stellar convection to 3D stellar convection, we aim to compare 3D hydrodynamic simulations to identically set-up 2D simulations, for a realistic pre-main sequence star. Methods. We compare statistical quantities related to convective flows including: average velocity, vorticity, local enstrophy, and penetration depth beneath a convection zone. These statistics were produced during stationary, steady-state compressible convection in the star’s convection zone. Results. Our simulations confirm the common result that 2D simulations of stellar convection have a higher magnitude of velocity on average than 3D simulations. Boundary conditions and the extent of the spherical shell can affect the magnitude and variability of convective velocities. The difference between 2D and 3D velocities is dependent on these background points; in our simulations this can have an effect as large as the difference resulting from the dimensionality of the simulation. Nevertheless, radial velocities near the convective boundary are comparable in our 2D and 3D simulations. The average local enstrophy of the flow is lower for 2D simulations than for 3D simulations, indicating a different shape and structuring of 3D stellar convection. We performed a statistical analysis of the depth of convective penetration below the convection zone using the model proposed in our recent study (Pratt et al. 2017, A&A, 604, A125). That statistical model was developed based on 2D simulations, which allowed us to examine longer times and higher radial resolution than are possible in 3D. Here, we analyze the convective penetration in 3D simulations, and compare the results to identically set-up 2D simulations. In 3D simulations, the penetration depth is as large as the penetration depth calculated from 2D simulations.

Multidimensional low-Mach number time-implicit hydrodynamic simulations of convective helium shell burning in a massive star

“…For this, 3D simulations of convective Heshell burning in a 25 M ⊙ star are presented and analyzed regarding general properties of the turbulent convection. In addition, we complement recent efforts to characterize convective boundary mixing by means of multidimensional simulations (e.g., Meakin & Arnett 2007;Woodward et al 2015;Jones et al 2017;Cristini et al 2017Cristini et al , 2019Pratt et al 2017Pratt et al , 2020Higl et al 2021).…”

Dynamics in a stellar convective layer and at its boundary: Comparison of five 3D hydrodynamics codes

“…The code has been benchmarked against a number of standard hydrodynamical test problems (e.g. Goffrey et al 2017) and has been applied to a number of stellar physics problems, including accretion (Geroux et al 2016) and convective overshooting (Pratt et al 2017, Pratt, J. et al 2020.…”

Convective core entrainment in 1D main-sequence stellar models

“…1 in Brott et al 2011) and asteroseismic frequencies (Aerts et al 2018). E-mail: l.j.a.scott@keele.ac.uk Both 3D hydrodynamics simulations and observations can be compared to 1D models incorporating CBM and other mixing processes, such as waves (Meakin & Arnett 2007;Jones et al 2017;Edelmann et al 2019;Müller 2020;Pratt et al 2020). Incorporating 3D hydrodynamics results, such as convective regions that grow as a result of entrainment, into 1D models also allows them to be studied on evolutionary time-scales.…”