A MASSIVELY PARALLEL EULERIAN-LAGRANGIAN METHOD FOR ADVECTION-DOMINATED TRANSPORT IN VISCOUS FLUIDS

Motivated by challenges in the Earth's mantle convection, we present a massively parallel implementation of an Eulerian-Lagrangian method for the advection-diffusion equation in the advection-dominated regime. The advection term is treated by a particle-based characteristics method coupled to a block-structured finite element framework. Its numerical and computational performance is evaluated in multiple two- and three-dimensional benchmarks, including curved geometries, discontinuous solutions, and pure advection, and it is applied to a coupled nonlinear system modeling buoyancy-driven convection in Stokes flow. We demonstrate the parallel performance in a strong and weak scaling experiment, with scalability to up to 147,456 parallel processes, solving for more than 5.2 x 10(10) (52 billion) degrees of freedom per time-step.