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983: Error: Internal Error in Geometry Decomposition

Why do I get the error message “Internal error in geometry decomposition”? This error means that COMSOL Multiphysics failed to resolve the geometry relations. If your geometry consists of several objects, the...
Version: All versions - Platform: All Platforms

973: My flux calculation seems wrong

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

964: Error: Failed to find a solution. Returned solution is not converged

I get this message: Failed to find a solution. The relative residual (0.28) is greater than the relative tolerance. Returned solution is not converged. Messages similar to this are returned for nonlinear problems...
Version: All versions - Platform: All Platforms

953: Error: Singular Matrix

What does the error message "Singular Matrix" mean? The problem is that the stiffness matrix of the linear system is singular and the linear solver cannot invert it. Examples of practical modeling situations where...
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952: Avoiding negative concentrations

Why do I get negative values of the concentration in my diffusion, convection and reaction model? Why do I see values that go below, or above, their lowest, or highest, possible values based upon the boundary...
Version: All versions - Platform: All Platforms

933: Troubleshooting graphics issues

Chances are that there is a graphics rendering problem if any of these symptoms show up: The graphics window is black It is not possible to mouse-select objects in the graphics window The COMSOL application crashes...
Version: All versions - Platform: All Platforms

913: Computing Time and Space Integrals

How do I compute integrals over space or time? What if I want to use the result of these integrals elsewhere in my model? The COMSOL Multiphysics architecture allows you to evaluate integrals in both space and time in...
Version: All versions - Platform: All Platforms

905: Modeling of step transitions

You may want to define loads, material properties, or boundary conditions that vary abruptly with respect to the solution, or with respect to time. This can, however, lead to a solution which is discontinuous in space...
Version: All versions - Platform: All Platforms

903: Could not obtain license for COMSOL Multiphysics GUI

Any of the following errors can appear for example if the COMSOL application has problems communicating with the license manager: License error: -15. Cannot connect to license server system. License error:...
Version: All versions - Platform: All Platforms

878: Should I use the RMS, the peak, or the instantaneous value to...

Should I use the RMS, the peak, or the instantaneous value to specify sources for electromagnetic fields? How can I specify the phase angle? The COMSOL Multiphysics formulation uses complex fields when solving...
Version: All versions - Platform: All Platforms