# [ICEM] Aspect ratio vs quality of a tetra mesh

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 September 13, 2012, 09:17 Aspect ratio vs quality of a tetra mesh #1 Senior Member   Ugly Kid Joe Join Date: Aug 2010 Posts: 193 Rep Power: 9 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.

 September 17, 2012, 08:28 #2 New Member   Join Date: Sep 2012 Posts: 8 Rep Power: 7 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

 September 17, 2012, 11:05 #3 Senior Member   Ugly Kid Joe Join Date: Aug 2010 Posts: 193 Rep Power: 9 Hello FVH, We both have the same question presently. Hopefully someone can answer to all our query. -vmlxb6

 September 18, 2012, 05:35 #4 New Member   Join Date: Sep 2012 Posts: 8 Rep Power: 7 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.

 September 25, 2012, 09:51 #5 Senior Member   AB Join Date: Sep 2009 Location: France Posts: 323 Rep Power: 15 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. haitham osman likes this.

 September 25, 2012, 13:21 @ Broly #6 Senior Member   Ugly Kid Joe Join Date: Aug 2010 Posts: 193 Rep Power: 9 That was very helpful. Thank you very much.

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