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 r η up to 1 0 4 .