Extreme-Scale Geodynamic Modelling with TerraNeo

Finely resolved Geodynamic mantle convection models are crucial to understand
the detailed physics governing major geological process and to infer
the mineralogical state of the Earth. Given the scale needed to globally
resolve features of the mantle such as unstable boundary layers
and asthenospheric flows where viscosity can change by around four orders of
magnitude within 50 km, traditional sparse matrix methods become unsuitable
due to their immense memory requirements. TerraNeo builds upon the
massively parallel matrix-free finite element framework HyTeG which uses
geometric multigrid solvers on block-structured hybrid tetrahedral grids.
The extreme scalability of HyTeG has been demonstrated previously, solving
Stokes problems with trillions (1e12) of unknowns, corresponding to ≃ 1
km global resolution of Earth’s mantle.
We discuss the features and scalability of TerraNeo with respect to the
numerical treatment of the truncated anelastic liquid approximation as a
model for mantle convection. The compute kernels are evaluated and verified
through geophysical applications, convergence studies, and community
benchmarks covering sharp viscosity variations, nonlinear rheologies and
mixed boundary conditions.