Discussion Forum

Hi all,

My COMSOL model only solves when the mesh size is "above" the predefined Normal size. When I increase the mesh resolution to "Fine" or higher, the step BiCGStab in the progress tab stalls at around 96%, and continues iterations forever until infinity trying to converge.

I'll describe the model briefly in this paragraph, and include an attachment of it. I'm simulating a very small, simple, conductive, flattened-conical tip (sliced in half vertically for symmetry) that radiates microwave (~6GHz) energy into the surrounding region via a coaxial lumped port. I'm using the Electromagnetic Waves, Frequency Domain physics module. The model behaves exactly as desired when the lower-limit of mesh quality is met, but endlessly iterates otherwise. I've tested varying the geometry and size of the tip to no avail. It seems that the minimum element size I can reach before causing non-convergence is about 3e-7 meters. (My model size is on the order of 1e-6 meters).

I'm so confused; there's obviously nothing wrong with the model setup/geometry/physics, because it solves for lower-quality meshes. Is this a computer memory problem? (I've got 8GB). Is there a lower-limit to element size / calculation in the [EMW, Frequency Domain] module that I've reached?

Thanks for the help.

Jon Michelson