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Converging a 2D-Axisymmetric Geometry for a reaction

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Hi guys,

I've been trying to get my 2D-axisymmetric reactor to converge, but to no avail.

Hence, I took a sample model, and took it apart to understand how it worked (www.comsol.com/model/fixed-bed-reactor-for-catalytic-hydrocarbon-oxidation-257)

One point that I noticed was that I could shrink the geometry (make the reactor thinner, shorter), but expanding it by just a small margin, led to inability to solve (persistent Newton's iterations, or an error message declaring the presence of 'degrees of freedom leading to NaN/InF'). No matter how I fine-tuned the meshing (adding in more domains, etc), there was no result the moment I breached the limits of the geometry by that small margin (e.g. 0.1m. Even finer margins (0.01m) still saw convergence).

There are no physical constraints that declare the limits of the geometry to be exactly fixed at the specified values. So my question is, based on the above information, could I request for any possibility of how this may be the case?

0 Replies Last Post 7 oct. 2014, 09:55 UTC−4
COMSOL Moderator

Hello Wu Jakes

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