All Solutions

License borrowing

Solution Number: 1016 Versions: All versions

How do I borrow license keys on a floating network license or a class-kit? License borrowing means that you can use COMSOL (for a limited time) with a Floating Network License (FNL) or a Class Kit license (CKL) without ...


Running COMSOL® in parallel on clusters

Solution Number: 1001 Versions: All versions

This 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 ...


Error: Internal Error in Geometry Decomposition

Solution Number: 983 Versions: All 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 ...


My flux calculation seems wrong

Solution Number: 973 Versions: All 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 ...


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

Solution Number: 964 Versions: All 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 ...


Error: Singular Matrix

Solution Number: 953 Versions: All 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 ...


Avoiding negative concentrations

Solution Number: 952 Applies to: COMSOL Multiphysics, CFD Module, Chemical Reaction Engineering Module, Electrodeposition Module, Microfluidics Module, Subsurface Flow Module, Mixer Module, Corrosion Module, Electrochemistry Module Versions: All 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 ...


Troubleshooting graphics issues

Solution Number: 933 Versions: All versions

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 ...


Computing Time and Space Integrals

Solution Number: 913 Versions: All 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 ...


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

Solution Number: 878 Applies to: AC/DC Module, Acoustics Module, COMSOL Multiphysics, MEMS Module, Plasma Module, RF Module, Semiconductor Module, Structural Mechanics Module, Wave Optics Module Versions: All 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 ...