The CIMNE researchers Santiago Badia, Alberto F. Martín, Eric Neiva and Francesc Verdugo from Large Scale Scientific Computing Group have recently published the article "A Generic Finite Element Framework on Parallel Tree-Based Adaptive Meshes" on SIAM Journal on Scientific Computing (Published online: 18 December 2020).
In this work, the researchers formally derive and prove the correctness of the algorithms and data structures in a parallel, distributed-memory, generic finite element framework that supports $h$-adaptivity on computational domains represented as forest-of-trees. The framework is grounded on a rich representation of the adaptive mesh suitable for generic finite elements that is built on top of a low-level, light-weight forest-of-trees data structure handled by a specialized, highly parallel adaptive meshing engine, for which they have identified the requirements it must fulfill to be coupled into our framework. Atop this two-layered mesh representation, they build the rest of the data structures required for the numerical integration and assembly of the discrete system of linear equations.
They consider algorithms that are suitable for both sub-assembled and fully assembled distributed data layouts of linear system matrices. The proposed framework has been implemented within the FEMPAR scientific software library, using p4est as a practical forest-of-octrees demonstrator. A strong scaling study of this implementation when applied to Poisson and Maxwell problems reveals remarkable scalability up to 32.2K CPU cores and 482.2M degrees of freedom. Besides, a comparative performance study of FEMPAR and the state-of-the-art deal.II finite element software shows at least comparative performance, and at most a factor of 2--3 improvement in the $h$-adaptive approximation of a Poisson problem with first- and second-order Lagrangian finite elements, respectively.
Keywords: partial differential equations, finite elements, adaptive mesh refinement, forest of trees, parallel algorithms, scientific software.