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Context. Multidimensional hydrodynamic simulations of convection in stellar interiors are numerically challenging, especially for flows at low Mach numbers. Methods. We explore the benefits of using a low-Mach hydrodynamic flux solver and demonstrate its usability for simulations in the astrophysical context. The time-implicit Seven-League Hydro (SLH) code was used to perform multidimensional simulations of convective helium shell burning based on a 25 M$_odot$ star model. The results obtained with the low-Mach AUSM$^{+}$-up solver were compared to results when using its non low-Mach variant AUSM$_mathrm{B}^{+}$-up. We applied well-balancing of the gravitational source term to maintain the initial hydrostatic background stratification. The computational grids have resolutions ranging from $180 times 90^2$ to $810 times 540^2$ cells and the nuclear energy release was boosted by factors of $3 times 10^3$, $1 times 10^4$, and $3 times 10^4$ to study the dependence of the results on these parameters. Results. The boosted energy input results in convection at Mach numbers in the range of $10^{-2}$ to $10^{-3}$. Standard mixing-length theory (MLT) predicts convective velocities of about $1.6 times 10^{-4}$ if no boosting is applied. Simulations with AUSM$^{+}$-up show a Kolmogorov-like inertial range in the kinetic energy spectrum that extends further toward smaller scales compared with its non low-Mach variant. The kinetic energy dissipation of the AUSM$^{+}$-up solver already converges at a lower resolution compared to AUSM$^{+}_{mathrm{B}}$ -up. The extracted entrainment rates at the boundaries of the convection zone are well represented by the bulk Richardson entrainment law and the corresponding fitting parameters are in agreement with published results for carbon shell burning.
Non-spherical structure in massive stars at the point of iron core collapse can have a qualitative impact on the properties of the ensuing core-collapse supernova explosions and the multi-messenger signals they produce. Strong perturbations can aid s
We present the first 3-dimensional, fully compressible gas-dynamics simulations in $4pi$ geometry of He-shell flash convection with proton-rich fuel entrainment at the upper boundary. This work is motivated by the insufficiently understood observed c
We find significant fluctuations of angular momentum within the convective helium shell of a pre-collapse massive star - a core-collapse supernova progenitor - which may facilitate the formation of accretion disks and jets that can explode the star.
Stars of sufficiently low mass are convective throughout their interiors, and so do not possess an internal boundary layer akin to the solar tachocline. Because that interface figures so prominently in many theories of the solar magnetic dynamo, a wi
(abridged) Context: The ratio of kinematic viscosity to thermal diffusivity, the Prandtl number, is much smaller than unity in stellar convection zones. Aims: To study the statistics of convective flows and energy transport as functions of the Prandt