Base de connaissances du support

Error: Internal Error in Geometry Decomposition

Solution numéro: 983 Versions: Toutes les versions

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 objects ...

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My Flux Calculation Seems Wrong

Solution numéro: 973 Versions: Toutes les versions

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 ...

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Error: Failed to Find a Solution. Returned Solution is Not Converged

Solution numéro: 964 Versions: Toutes les versions

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 ...

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Error: Singular Matrix

Solution numéro: 953 Versions: Toutes les versions

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 this ...

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Avoiding Negative Concentrations

Solution numéro: 952 Se réfère à: CFD Module, Chemical Reaction Engineering Module, COMSOL Multiphysics, Corrosion Module, Electrochemistry Module, Electrodeposition Module, Microfluidics Module, Mixer Module, Subsurface Flow Module Versions: Toutes les versions

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 ...

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Troubleshooting Graphics Issues

Solution numéro: 933 Versions: Toutes les versions

I am experiencing graphics issues in COMSOL Multiphysics, what can I do about it? This entry is meant as listing general strategies when experiencing graphics issues in COMSOL Multiphysics. More problem-specific fixes ...

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Computing Time and Space Integrals

Solution numéro: 913 Versions: Toutes les versions

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 ...

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How does COMSOL Multiphysics handle complex-valued numbers and problems in the frequency domain?

Solution numéro: 878 Se réfère à: AC/DC Module, Acoustics Module, COMSOL Multiphysics, MEMS Module, Plasma Module, RF Module, Semiconductor Module, Structural Mechanics Module, Wave Optics Module Versions: Toutes les versions

How does COMSOL Multiphysics handle complex-valued numbers and problems in the frequency domain? Should I use the RMS, the peak, or the instantaneous value to specify sources in models being solved in the frequency ...

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What Does Degrees of Freedom (DOFs) Mean in COMSOL Multiphysics?

Solution numéro: 875 Versions: Toutes les versions

What does degrees of freedom (DOFs) mean in COMSOL Multiphysics? The solution time and memory requirements are strongly related to the number of degrees of freedom in the model. It is often desirable to be able to ...

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Modeling of Step Transitions

Solution numéro: 905 Versions: Toutes les versions

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 ...

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