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-   -   [ICEM] How to improve bad quality elements that are obtained after creating prism layers? (https://www.cfd-online.com/Forums/ansys-meshing/156690-how-improve-bad-quality-elements-obtained-after-creating-prism-layers.html)

Rohith Giridhar July 10, 2015 14:00

How to improve bad quality elements that are obtained after creating prism layers?
 
2 Attachment(s)
Hi All,

I have a volume mesh with a minimum quality of 0.4289. When I create the prism layers on the blade surface using this volume mesh, the quality of the tetra elements become very poor with a minimum quality of 3.74823e-005. All these bad elements which have a quality less than 0.3 are found near the blade surface as shown in attached figure 1. I found some suggestions on the prism layer settings from this forum and from Simon's Prism/No Pyramids PPT and these were the following changes in the Prism mesh set up that I have made which reduced the number of many bad quality elements significantly. They are:

a.) Minimum prism quality=0.000001
b.) Ortho weight=0.1
c.) Fillet ratio=0.5
d.) Maximum prism angle=180.
e.) Prism height limit factor=1
f.) Smoothing options=> Number of smoothing steps:0
g.) Advanced Prism Meshing Parameters: Auto-Reduction:Check.

But, I still have some bad quality elements and I don't know how to improve their quality. Most of these bad quality elements are located near the tip of the blade as shown in attached figure 2.

How do I improve the quality of these elements? Also, what would be the acceptable quality for elements in the mesh that I must have before transferring this mesh to Fluent? And are there any other parameters that I need to check and improve before transferring this mesh to Fluent?

Could anybody please let me know regarding these? Thank you!:)

**Anny** July 11, 2015 02:49

I also had some trouble with a blade surface... maybe you find something in my old post http://www.cfd-online.com/Forums/ans...d-quality.html
good luck

Rohith Giridhar July 11, 2015 18:04

2 Attachment(s)
Hi Anny,

Thank you for your reply. I saw your post and used those suggestions. I had already generated a Delauney mesh for my volume mesh and had reduced the curvature proximity limit. But this time I split the prism layers and redistributed based on the initial height. The number of bad elements decreased.

As, suggested in the post, I tried to smooth all the tetra elements above 0.4 by freezing other elements but was unable to do so.
I have attached a picture of the bad tetra elements that have a quality less than 0.4 which seems to be scattered around the blade.

I have also attached a picture of all the bad quality elements upto 0.3 now and I see that all of them are located along the trailing edge of the blade only.

I noticed that in your post you had mentioned that the thickenss of your trailing edge was only 1.5mm and that could be the reason for bad elements.
My trailing edge is sharp with no thickness. Could this be the reason for obtaining all these bad elements?
Could you please let me know how I could go about with this?
Thank you!


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