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Increasing local mesh density with second block

Posted Aug 10, 2012, 9:16 a.m. EDT Low-Frequency Electromagnetics, Mesh, Modeling Tools & Definitions, Parameters, Variables, & Functions Version 4.0a 2 Replies

Stephen Cross
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Hi,

Just a quick question regarding how legitimate a technique I've used is.

I'm modelling magnets and want to plot the force as a function of distance from the magnets. I've already got this working and have got my 1D force plot; however, it's not as smooth as I'd have liked. I know I can improve this by increasing the overall mesh density in my air sphere. I was wondering if it's legitimate for me to use a second box (a very narrow box, which runs the length of the distance over which I'm measuring), as this increases the local mesh density in the area I'm interested in. The second box I've used is filled with air, as this is what is in the larger sphere I'm performing the simulation in.

The force curve I got doing this looks exactly as I'd like (i.e. very smooth), but I just wanted to check this is an acceptable way of increasing mesh density.

Any advice on this would be greatly appreciated.

Thanks
Stephen
2 Replies Last Post Aug 11, 2012, 9:37 a.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Aug 11, 2012, 3:28 a.m. EDT
Hi

the force calcuations are derived from field gradients, so if your local meshing denisty is made higher where it counts it will improve, but you need a reasonable mesh density outside this local region too, else the field is poorly resolved at the boundary of the region of higher mesh density.
My suggestion is to run once with twice as dense mesh (everywhere) and se how the result change, not only the "smoothness" but also the absolute value(s) field

--
Good luck
Ivar
Hi the force calcuations are derived from field gradients, so if your local meshing denisty is made higher where it counts it will improve, but you need a reasonable mesh density outside this local region too, else the field is poorly resolved at the boundary of the region of higher mesh density. My suggestion is to run once with twice as dense mesh (everywhere) and se how the result change, not only the "smoothness" but also the absolute value(s) field -- Good luck Ivar
Stephen Cross
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Posted: 1 decade ago Aug 11, 2012, 9:37 a.m. EDT
Thank you for the response. I shall give this a go.

Stephen
Thank you for the response. I shall give this a go. Stephen

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