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Solver

1250: Running parametric sweeps, batch sweeps, and cluster sweeps from...

This solution describes how to launch a parametric sweep, a batch sweep, or a cluster sweep simulation in COMSOL Multiphysics® from the command line. Short Summary Model methods are presented as a concept to modify...
Version: All versions - Platform: All Platforms

1249: Solution number is out of range

You compute a distributed parametric sweep on a cluster. When processing the results some values are missing or you get errors such as "The solution number is invalid" or "Solution number is out of range". This issue...
Version: 5.3a - Platform: All Platforms

1245: Solving Models with Pulsed Loads in Time

I am solving a transient model which has loads that change instantaneously in time, but the solver appears to be missing some of these changes in the loads. How to I get the solver to correctly recognize when the load...
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1244: Solving Wave-Type Problems with Step Changes in the Loads

I am solving a transient model and am expecting the solution to oscillate over time in response to step changes in the loads. How should I set up such a model? What solver changes should I make? Certain models will...
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1240: Manually Setting the Scaling of Variables

The default behavior of the software is to assume a different scaling for each set of variables in your model. These scale factors are by default automatically determined, but sometimes may need to be manually...
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1213: Manually setup the geometric multigrid solver

The 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...
Version: All versions - Platform: All Platforms

1172: Solving time dependent models with inconsistent initial values

A 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...
Version: All versions - Platform: All Platforms

1127: Improving convergence in nonlinear time dependent models

When 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 ...
Version: All versions - Platform: All Platforms

1118: Resolving time-dependent waves

I am solving a time-dependent wave-type problem, what mesh and solver settings should I adjust for better accuracy and runtimes? The accuracy of a time-dependent model solving for electromagnetic, acoustic,...
Version: All versions - Platform: All Platforms

1102: Structural Contact Modeling Guidelines

This 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...
Version: All versions - Platform: All Platforms