Scalable domain decomposition solver for three-grid immersed finite element method

• Date: 30. 10. 2025
• Time: 14:00 - 15:30
• Address:
  Sokolovská 83, Praha
• Room: K3
• Speaker: Jakub Šístek

Immersed boundary finite element method (FEM) presents an attractive approach to simulations avoiding the generation of large body-fitted meshes. This can be tedious and challenging for complex geometries as well as for very fine adaptive meshes distributed over a parallel supercomputer. However, the price to pay are more complicated formulations for the weak enforcement of Dirichlet boundary conditions, poor conditioning of stiffness matrices, and nonstandard numerical integration at the boundary. [1] E. Febrianto, J. Šístek, P. Kůs, M. Kecman, and F. Cirak. A three-grid high-order immersed finite element method for the analysis of CAD models. Computer-Aided Design, 173:103730, 2024. We develop multilevel balancing domain decomposition based on constraints (BDDC) method tailored to the solution of the linear systems arising in the context of immersed boundary FEM with parallel adaptive grid refinement using Z-curves (based on the p4est library). One crucial challenge is presented by fragmenting of subdomains, which has two sources: i) the partitioning strategy based on space-filling curves, and ii) extraction of the elements contributing to the stiffness matrix. Numerical results for large-scale Poisson and linear elasticity problems on complex geometries from engineering will be presented. The presentation is largely based on our recent paper [1]. This is joint work with Monika Balázsová, Fehmi Cirak, Eky Febrianto, Matija Kecman, Pavel Kůs, and Josef Musil.