Solver
Manually setup the geometric multigrid solver
Solution Number: 1213 Versions: All versionsThe geometric multigrid solver accelerates the convergence of the iterative solver by solving the finite element problem on a series of meshes rather than a single one. The multigrid algorithm starts with the initial ...
Solving time dependent models with inconsistent initial values
Solution Number: 1172 Versions: All versionsA common mistake when setting up transient models is to have initial conditions that are inconsistent with the loads and boundary conditions. This occurs most often when running transient fluid flow studies, but the ...
Improving Convergence of Nonlinear Stationary Models
Solution Number: 103 Versions: All versionsStationary (time-invariant) models with nonlinearities may converge very slowly. A nonlinearity can be introduced into the model either in the governing equation, or by making any of the material properties, loads, or ...
Improving convergence in nonlinear time dependent models
Solution Number: 1127 Versions: All versionsWhen I look at the Solver Log of a time dependent model, I see that the NLFail column has non-zero entries: Step TimeStepsize Res JacSolOrderTfailNLfailLinErrLinRes 0 0-out 23208e-14 3.5e-15 ...
Structural Contact Modeling Guidelines
Solution Number: 1102 Applies to: MEMS Module, Structural Mechanics Module Versions: All versionsThis article contains guidance for solving models that include structural contact, and the procedures that should be followed to achieve a converged solution. Background Structural contact modeling is a highly non ...
COMSOL and Multithreading
Solution Number: 1096 Versions: All versionsThis solution describes how COMSOL takes advantage of multicore computers. COMSOL supports two mutual modes of parallel operation: shared-memory parallelism and distributed-memory parallelism (cluster support). Shared ...
BDF, Generalized Alpha, and Runge-Kutta Methods
Solution Number: 1062 Versions: All versionsWhat numerical methods are available when using a Time-Dependent Solver? What are their relative benefits and when should I use them? The Time-Dependent Solver offers three different time stepping methods: The ...
Error: "Out of memory"
Solution Number: 1030 Versions: All versionsI get an error message, that contains the words Out of memory, for example: Out of memory during LU factorization. or Out of memory during assembly # Background Before resolving this issue, you should go through ...
Running COMSOL® in Parallel on Clusters
Solution Number: 1001 Versions: All versionsThis solution describes how you enable distributed parallelization (cluster jobs) in COMSOL Multiphysics®. COMSOL supports two mutual modes of parallel operation: shared-memory parallel operations and distributed ...
My Flux Calculation Seems Wrong
Solution Number: 973 Versions: All versionsI am solving a diffusion-like problem in COMSOL Multiphysics and discovered that boundaries that are defined with insulation/symmetry conditions have an integrated value of the normal component of the flux that is far ...