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[ICEM] Aspect ratio vs quality of a tetra mesh

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Old   September 13, 2012, 09:17
Default Aspect ratio vs quality of a tetra mesh
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Hello,

I have this geometry where I have used tetra meshing throughout. When I checked the histogram of quality values I found that majority of my elements are
between 0.45 to 1 how ever the histogram of aspect ratio looks different. My question is how is quality defined in ICEM.
The documentation says for a tetra element, the quality is calculated as the aspect ratio of the tetra element. So that means histogram of quality and aspect ratio should be the same. I would appreciate if someone could throw some light on this.
Also when can an individual tell that the tetra mesh is good enough. Is there a general criteria used ?

Thank you very much for all your help. appreciate.
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Old   September 17, 2012, 08:28
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Hi vmlxb6,

My question is almost the same and at the moment i'm trying to find out why the histogramm of aspect ratio is so different to the histogramm of quality. Do you know how quality is defined in Icem? What is the general criteria?
Thank you for your help
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Old   September 17, 2012, 11:05
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Hello FVH,

We both have the same question presently. Hopefully someone can answer to all our query.

-vmlxb6
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Old   September 18, 2012, 05:35
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Hi vmlxb6,

It is reallyy difficult to get an answer for this question but at least i found a little help in the icemhelp guide. On page 395 and the following you will find some definition. The criterion quality is calculated differently for each element type. For quad and hexa., the quality is calculated as the determinant. A determinant value of 1 would indicate a perfectly regular mesh element, 0 would indicate an element degenerate in one or more edges.
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Old   September 25, 2012, 09:51
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It's because you check the quality for tetra, but also for tri or even penta (if you have some).
Go to Edit Mesh -> Display Mesh Quality ->
Select only the tetra, and check for quality and aspect ratio.
You will find the same histogram.

The aspect ratio is only calculated for tri and tetra.
But quality is also calculated for penta.
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Old   September 25, 2012, 13:21
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That was very helpful. Thank you very much.
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