Support Knowledge Base

How, and why, switch between a fully coupled and a segregated approach to solving a multiphysics model? How, and why, switch between the direct and iterative linear system solver? Fully Coupled versus Segregated...
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I am solving a Multiphysics problem involving electromagnetics and heat transfer. The electromagnetic fields are varying at a constant frequency, and the period is very short compared to the timespan over which the...
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My models contain a lot of solution data, and I do not want my file sizes to get too large, it takes a lot of disk space. What can I do to reduce file size? Will this reduce the time it takes to solve the model? File...
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I am solving a transient model and changed the stepsize in the Times: field in the Study Settings, but the solver is still taking exactly the same timesteps. It seems the timesteps that the solver is taking are not...
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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...
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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

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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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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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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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