The ANTARES code has been designed for simulation of astrophysical flows in a variety of situations, in particular in the context of stellar physics. Here, we describe extensions as necessary to model the interaction of pulsation and convection in cl
assical pulsating stars. These extensions encomprise the introduction of a spherical grid, movable in the radial direction, specific forms of grid-refinement and considerations regarding radiative transfer. We then present the basic parameters of the cepheid we study more closely. For that star we provide a short discussion of patterns of the H+HeI and the HeII convection zones and the interaction with pulsation seen in the pdV work or atmospheric structures.
We discuss the general design of the ANTARES code which is intended for simulations in stellar hydrodynamics with radiative transfer and realistic microphysics in 1D, 2D and 3D. We then compare the quality of various numerical methods. We have applie
d ANTARES in order to obtain high resolution simulations of solar granulation which we describe and analyze. In order to obtain high resolution, we apply grid refinement to a region predominantly occupied by an exploding granule. Strong, rapidly rotating vortex tubes of small diameter (~100 km) generated by the downdrafts and ascending into the photosphere near the granule boundaries evolve, often entering the photosphere from below in an arclike fashion. They essentially contribute to the turbulent velocity field near the granule boundaries.
Using grid refinement, we have simulated solar granulation in 2D. The refined region measures 1.97*2.58 Mm (vertical*horizontal). Grid spacing there is 1.82*2.84 km. The downflows exhibit strong Kelvin-Helmholtz instabilities. Below the photosphere,
acoustic pulses are generated. They proceed laterally (in some cases distances of at least the size of our refined domain) and may be enhanced when transversing downflows) as well as upwards where, in the photosphere they contribute significantly to turbulence (velocity gradients, etc.) The acoustic pulses are ubiquitous in that at any time several of them are seen in our high-resolution domain. Their possible contributions to p-mode excitation or heating of the chromosphere needs to be investigated.
