Achievable efficiency of numerical methods for simulations of solar surface convection.

We investigate the achievable efficiency of both the time and the space discretisation methods used in Antares for mixed parabolic–hyperbolic problems. We show that the fifth order variant of WENO combined with a second order Runge–Kutta scheme is not only more accurate than standard first and second order schemes, but also more efficient taking the computation time into account. Then, we calculate the error decay rates of WENO with several explicit Runge–Kutta schemes for advective and diffusive problems with smooth and non-smooth initial conditions. With this data, we estimate the computational costs of three-dimensional simulations of stellar surface convection and show that SSPRK(3,2) is the most efficient scheme considered in this comparison.