The Krylov space is also reused in the case of solving again, for nonlinear, parametric, or time-dependent solvers. Now the restart can be seamless and with a much smaller penalty at restart in a typical situation. This makes the method much more useful beyond the restart point, where before the convergence could often deteriorate badly at a restart. When activated, and when the GMRES method restarts, instead of restarting from an empty Krylov space, the method reuses and improves the space already built up. The popular iterative solver GMRES has a new option in COMSOL Multiphysics ® version 5.6: Use GCRO-DR. View screenshot New Option for GMRES: Reuse of the Krylov Space Utilizing cluster computing, it is possible to use FEAST in parallel for improved performance. One important aspect of FEAST is that different linear systems of equations are solved for each quadrature point along the contour and these problems are independent. The method further supports automatic estimation of the number of eigenvalues within the contour, important for robustness and performance. It supports the usual symmetric or nonsymmetric formulations in COMSOL Multiphysics ®. FEAST: A New Eigenvalue SolverĬOMSOL Multiphysics ® version 5.6 comes with an interface for FEAST, which is a solver designed to find eigenvalues within an ellipse-shaped contour in the complex plane. and the memory peak is 118 GB when using 10 cluster nodes each with 48 cores (2x Intel ® Xeon® Platinum 8260 24 cores). The wall-clock computation time is 2900 sec. The model has 30 million degrees of freedom, which are split into 10 domains. number of nodes.Ĭar cabin acoustics analysis for 5 kHz solved with the new Absorbing boundary condition for the Domain Decomposition (Schur) method. The graphs below show the performance as computation time vs. In addition, the overlapping Domain Decomposition (Schwarz) method is used as a preconditioner to GMRES with the multigrid method as a domain solver (denoted DD). The solvers used in the comparison are the algebraic multigrid solver ( SA-AMG) as a preconditioner to GMRES with the Symmetrically Coupled Gauss-Seidel smoother (denoted MG in the comparison graphs). In this comparison, COMSOL Multiphysics ® version 5.5 update 3 and version 5.6 are installed on a cluster where each node has 48 cores (2x Intel ® Xeon® Platinum 8260 24 cores). The model used in the benchmark has a refined mesh, as compared to the Application Gallery version, with 6.3 million degrees of freedom on a 16-node cluster. Furthermore, the most important smoothers used in the multigrid method are now more efficient, in particular for cluster computing.Īs an illustration of the improvement, consider the following CFD benchmark of an Ahmed Body featuring turbulent flow. The reduction is significant for both multicore and cluster computing. In particular, the memory requirements are reduced for Jacobian matrix assembly as well as for the algebraic multigrid preconditioner. Performance Improvements for Multicore and Cluster ComputingĬOMSOL Multiphysics ® version 5.6 includes several performance improvements for the solution process. Learn about all of the updates relating to studies and solvers below. COMSOL Multiphysics ® version 5.6 includes faster and more memory-lean multicore and cluster computing, new Domain Decomposition functionality, a new eigenvalue solver, and more.
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