Discussion Forum

Posted: 1 decade ago Jul 14, 2014, 1:55 a.m. EDT

[QUOTE] Local mesh transformation failed. - Detail: Coordinate evaluation failed What does these word means? [/QUOTE] I just got this error when my General Extrusion operator was messed up. There are 3 sets of coords in General Extrusion operators: 1. The x and y coords that are specific to this operator. They are the coordinates of the "intermediate space" that only this operator knows about and works with. 2. The source map coords. In my case I am defining the operator on a 2D axisymmetric context, so here they are intuitively prefilled by default as "r" and "z", which means that the intermediate space x and y coordinate axes correspond exactly with the r and z coordinate axes of this axisymmetric space. 3. The destination map coords. Suppose I was making the data available to a typical 3D x,y,z space. Then the destination map would be defining x and y in terms of x, y and z, where the first x and y are different from the second x and y. This is extremely confusing, so I renamed the x,y,z coordinates to u,v,w, by going to the "Model 1 (mod1)" node in the tree and changing the names. Now it makes a lot more sense, so that the destination map becomes something like x = -0.8*u, y = -0.8*v. Much easier to read than x = -0.8*x, y = -0.8*y. Ideally Comsol wouldn't allow these sort of name collisions, but it does, and it's also the default behaviour. The other confusing thing is that Comsol prefills the destination map x-expression and y-expression as r,z (i.e. the source map coords, even though this never makes sense, because the operator would then map everything to itself, and would be redundant). In general, the destination map should use the coords of the space *from which you would like to use the local data*, equivalently *to which you are extruding*. Thus, I would use the coords u,v,w in the general extrusion operator defined under the "Model 2 (mod2)" node, even though these coords are defined in "Model 1". It's probably for this reason that you could type anything into the "x-expression" and "y-expression" fields, and Comsol won't highlight it as an error (I guess it "doesn't know" where you are intending to use the general extrusion operator from, so it can't validate; this can be fixed by a better design), but when you actually try to solve the study, it will give the error you report above. Which, I should add, makes total sense, in hindsight.

Posted: 9 years ago Aug 11, 2015, 4:20 a.m. EDT

I got this error after I had imported a geometry from an mphbin file. apparenty the software could not match the coordinates in this imprted geometry to the other geometries where general extrusion coupling was used. After I rebuilt the geometry, the model started working. Cheers.

Posted: 9 years ago Aug 26, 2015, 2:31 p.m. EDT

After I ran into the same error twice I guess the place to look for to solve this problem is the definitions of the extusion coupling. You have to be sure that your couplings are correctly defined. Cheers