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Hengky August 11, 2005 11:01

Highly skewed elements
 
Dear Forum, I always have highly skewed elements in meshing my geometry. I was wondering if someone could tell me how to avoid those highly skewed elements. Thank you. I appreciate it

Swarup August 11, 2005 12:49

Re: Highly skewed elements
 
High skewing can happen due to excessive mesh refinement in case of tri/tetra meshes. the problem can be acute at wall boundaries. why not try other mesh types or work with coarse mesh first and then selectively refine it?

Swarup

Jason August 11, 2005 13:17

Re: Highly skewed elements
 
There are a lot of things that can cause highly skewed elements. Lets say you want to mesh a surface with a .1mm Face mesh... but there are two vertices on the surface that are only .0001mm apart... since Gambit will place a node at any vertice, then the third element will be about .1mm away... now you have a triangle with one edge of about .0001mm and two edges of about .1mm... this is a skewed element. This is just one example of what can cause a skewed element... another cause is two edges that come together at an acute angle, the element created in the corner will be skewed... in 3D there's many more possible causes. Every case is unique. It can almost always be attributed back to a problem with the geometry. First you need to find where the skewed elements are (you can use the Examine Mesh Tool... icon on the bottom right of the screen... looks like a yellow grid with a magnifying glass over it). Once you know where they are, you need to think about what's causing them. It's rare that there is a highly skewed element "floating" out in the middle of the volume. If this happens, then it may be due to over refinement. Odds are though that the problem cells are located on a surface and are a result of the geometry. Once you know where they are and what caused the problem, you can work out a way to correct the problem (whether it's merging edges and/or faces, or splitting edges and/or face or actually splitting the volume into smaller, easier to mesh volumes).

Hope this helps, and good luck, Jason


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