Print Email Facebook Twitter FROSch Preconditioners for Land Ice Simulations of Greenland and Antarctica Title FROSch Preconditioners for Land Ice Simulations of Greenland and Antarctica Author Heinlein, A. (TU Delft Numerical Analysis) Perego, Mauro (Sandia National Laboratories) Rajamanickam, Sivasankaran (Sandia National Laboratories) Date 2022 Abstract Numerical simulations of Greenland and Antarctic ice sheets involve the solution of large-scale highly nonlinear systems of equations on complex shallow geometries. This work is concerned with the construction of Schwarz preconditioners for the solution of the associated tangent problems, which are challenging for solvers mainly because of the strong anisotropy of the meshes and wildly changing boundary conditions that can lead to poorly constrained problems on large portions of the domain. Here, two-level generalized Dryja-Smith-Widlund (GDSW)-type Schwarz preconditioners are applied to different land ice problems, i.e., a velocity problem, a temperature problem, as well as the coupling of the former two problems. We employ the message passing interface (MPI)- parallel implementation of multilevel Schwarz preconditioners provided by the package FROSch (fast and robust Schwarz) from the Trilinos library. The strength of the proposed preconditioner is that it yields out-of-the-box scalable and robust preconditioners for the single physics problems. To the best of our knowledge, this is the first time two-level Schwarz preconditioners have been applied to the ice sheet problem and a scalable preconditioner has been used for the coupled problem. The preconditioner for the coupled problem differs from previous monolithic GDSW preconditioners in the sense that decoupled extension operators are used to compute the values in the interior of the subdomains. Several approaches for improving the performance, such as reuse strategies and shared memory OpenMP parallelization, are explored as well. In our numerical study we target both uniform meshes of varying resolution for the Antarctic ice sheet as well as nonuniform meshes for the Greenland ice sheet. We present several weak and strong scaling studies confirming the robustness of the approach and the parallel scalability of the FROSch implementation. Among the highlights of the numerical results are a weak scaling study for up to 32 K processor cores (8 K MPI ranks and 4 OpenMP threads) and 566 M degrees of freedom for the velocity problem as well as a strong scaling study for up to 4 K processor cores (and MPI ranks) and 68 M degrees of freedom for the coupled problem. Subject domain decomposition methodsGDSW coarse spacesmonolithic Schwarz preconditionersmultiphysics simulationsparallel computing To reference this document use: http://resolver.tudelft.nl/uuid:b19efdbc-73f0-46f4-8599-98d4d05458b6 DOI https://doi.org/10.1137/21M1395260 Embargo date 2023-07-01 ISSN 1064-8275 Source SIAM Journal on Scientific Computing, 44 (2), B339-B367 Bibliographical note Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public. Part of collection Institutional Repository Document type journal article Rights © 2022 A. Heinlein, Mauro Perego, Sivasankaran Rajamanickam Files PDF 21m1395260.pdf 3.04 MB Close viewer /islandora/object/uuid:b19efdbc-73f0-46f4-8599-98d4d05458b6/datastream/OBJ/view