Adaptive Mesh Refinement for conservative systems:
multi-dimensional efficiency evaluation

R. Keppens, M. Nool, G. Tóth and J.P. Goedbloed

Obtainable computational efficiency is evaluated when using an Adaptive Mesh Refinement (AMR) strategy in time accurate simulations governed by sets of conservation laws. For a variety of 1D, 2D, and 3D hydro- and magnetohydrodynamic simulations, AMR is used in combination with several shock-capturing, conservative discretization schemes. Solution accuracy and execution times are compared with static grid simulations at the corresponding high resolution and time spent on AMR overhead is reported. Our examples reach corresponding efficiencies of 5 to 20 in multidimensional calculations and only 1.5 to 8 per cent overhead is observed. For AMR calculations of multi-dimensional magnetohydrodynamic problems, several strategies for controlling the divergence B = 0 constraint are examined. Three source term approaches suitable for cell-centered magnetic field representations are shown to be effective. For 2D and 3D calculations where a transition to a more globally turbulent state takes place, it is advocated to use an approximate Riemann solver based discretization at the highest allowed level(s), in combination with the robust Total Variation Diminishing Lax-Friedrichs method on the coarser levels. This level-dependent use of the spatial discretization acts as a computationally efficient, hybrid scheme.