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Problem transforming the Transport and Adsorption example to cylindrical geometry

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Hi,

I need to set up a model describing adsorption on the wall of a cylindrical tube. I thought the Transport and Adsorption example in Multiphysics Modeling Guide (p. 32) would be a good starting point as it has the same boundary saturation mechanism as I would like to include in my own model.

However, when entering the equation for the weak term on the boundary, the entered expression is simple replaced by a zero. I suspected problems already when trying to add the weak form problem. It could not be found under 2D axial symmetry, so I had to select 2-D geometry. Does this make sense?

As I'm not an experienced user of Comsol, I must be overlooking something fundamental.

...K. Henneberg

1 Reply Last Post Mar 23, 2010, 8:26 a.m. EDT

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Posted: 1 decade ago Mar 23, 2010, 8:26 a.m. EDT
Regarding my stated problem I've advanced further and found out that leaving out the tangential derivative in the x-direction makes the user interface accept the weak boundary term. It is now logical to me that an axi-symmetric problem only have change in the longitutinal direction. It seems, that the y-direction in the weak boundary formulation corresponds to the z-axis in the axi-symmetric formulation, but I'm merely guessing.

There is a lot to learn from the example models comming witht he Comsol installation. Unfortunately they seem only to be sorted based on the application area, not on what features of Comsol they demonstrate.

...Kaj Henneberg
Regarding my stated problem I've advanced further and found out that leaving out the tangential derivative in the x-direction makes the user interface accept the weak boundary term. It is now logical to me that an axi-symmetric problem only have change in the longitutinal direction. It seems, that the y-direction in the weak boundary formulation corresponds to the z-axis in the axi-symmetric formulation, but I'm merely guessing. There is a lot to learn from the example models comming witht he Comsol installation. Unfortunately they seem only to be sorted based on the application area, not on what features of Comsol they demonstrate. ...Kaj Henneberg

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