Multigrid-based simulation code for mantle convection in spherical shell using Yin–Yang grid

A new simulation code of mantle convection in a three-dimensional spherical shell is presented. Major innovation of the code comes from an combination of two numerical techniques, namely Yin–Yang grid and ACuTE algorithm, which we had developed for large-scale simulations of solid earth sciences. Benchmark comparisons for the steady convection for low Rayleigh numbers (Ra  ) with previous calculations revealed that accurate results are successfully reproduced not only for isoviscous cases but also for the cases where the mild temperature-dependence of viscosity is included. We also demonstrated that our code can reproduce the change in convective flow patterns into the “sluggish-lid” regime with increasing the viscosity variation rηrη up to 104104.