Stabilized Asynchronous Fast Adaptive Composite Multigrid using Additive Damping

Murray, Charles D.; Weinzierl, Tobias

Abstract

Multigrid solvers face multiple challenges on parallel computers. Two fundamental ones read as follows: Multiplicative solvers issue coarse grid solves which exhibit low concurrency and many multigrid implementations suffer from an expensive coarse grid identification phase plus adaptive mesh refinement overhead. We propose a new additive multigrid variant for spacetrees, that is, meshes as they are constructed from octrees and quadtrees: It is an additive scheme, that is, all multigrid resolution levels are updated concurrently. This ensures a high concurrency level, while the transfer operators between the mesh levels can still be constructed algebraically. The novel flavor of the additive scheme is an augmentation of the solver with an additive, auxiliary damping parameter per grid level per vertex that is in turn constructed through the next coarser level—an idea which utilizes smoothed aggregation principles or the motivation behind AFACx: Per level, we solve an additional equation whose purpose is to damp too aggressive solution updates per vertex which would otherwise, in combination with all the other levels, yield an overcorrection and, eventually, oscillations. This additional equation is constructed additively as well, that is, is once more solved concurrently to all other equations. This yields improved stability, closer to what is seen with multiplicative schemes, while pipelining techniques help us to write down the additive solver with single‐touch semantics for dynamically adaptive meshes.

Citation

Murray, C. D., & Weinzierl, T. (2021). Stabilized Asynchronous Fast Adaptive Composite Multigrid using Additive Damping. Numerical Linear Algebra with Applications, 28(3), Article e2328. https://doi.org/10.1002/nla.2328

• Journal Article Type: Article
• Acceptance Date: Jul 5, 2020
• Online Publication Date: Aug 24, 2020
• Publication Date: 2021-05
• Deposit Date: May 25, 2020
• Publicly Available Date: Aug 25, 2020
• Journal: Numerical Linear Algebra with Applications
• Print ISSN: 1070-5325
• Electronic ISSN: 1099-1506
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 28
• Issue: 3
• Article Number: e2328
• DOI: https://doi.org/10.1002/nla.2328
• Public URL: https://durham-repository.worktribe.com/output/1263767
• Related Public URLs: https://arxiv.org/abs/1903.10367