Speaker: Dr. Rob Falgout, Center for Applied Scientific Computing (CASC) at Lawrence Livermore National Laboratory (LLNL)

Abstract: The multigrid reduction in time (MGRIT) method is a parallel multigrid-in-time solver designed to be as non-intrusive as possible and take advantage of existing simulation codes and techniques. This has worked well for parabolic equations, but parallel-in-time methods for advection-dominated hyperbolic problems have proven difficult to develop. In previous work, we demonstrated the effectiveness of a modified semi-Lagrangian coarse-grid operator for speeding up the parallel solution of high-order discretizations of variable-wave-speed linear advection problems in both 1D and 2D. We have also recently extended this technique for solving nonlinear hyperbolic conservation laws, including the inviscid Burgers and Buckley-Leverett equations. In this talk, we will present further developments for solving linear and nonlinear systems of hyperbolic PDEs such as the acoustic equations, shallow water equations, and Euler equations. Joint work with: Hans De Sterck, Oliver A. Krzysik, and Jacob B. Schroder.

Short bio of Dr. Rob Falgout: Rob is a computational mathematician in the Center for Applied Scientific Computing (CASC) at Lawrence Livermore National Laboratory (LLNL). He is the project leader for the hyper scalable linear solvers project and the XBraid parallel time integration project. Rob earned his PhD in Applied Mathematics at the University of Virginia in 1991 under James Ortega and joined LLNL as a postdoc that same year. He worked initially on concurrent BLAS algorithms and later served as the technical leader for the ParFlow groundwater flow project. Rob was named LLNL Distinguished Member of Technical Staff in 2018 and SIAM Fellow in 2021. He is also the 2022 recipient of the SIAM Activity Group on Supercomputing Career Prize. Webpage: https://people.llnl.gov/falgout2