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hadikhayyamian June 16, 2012 13:48

2D to 3D block by rotation
3 Attachment(s)
Hi all,
I would like to make 3d mesh by blocking first 2d geometyry and then rorate around x-axis and so reaching my final 3d.

I attached my 2d mesh and then my parameters to setup 3D block in the 2nd figure. the third figure which shows 3D results is not coorectly generated since the mesh has changed.

Can anyone help!


Far June 19, 2012 08:28

your question and figures are not clear. Please attach files if possible and some new pics

hadikhayyamian June 19, 2012 10:12

Dear Far; thanks I sent to your mail.

this is 2D version of the geomtry which I wanted to rotate its block around x axis (point 0,0,0). you can try your self. my problem is that the rotated block does not have true mesh as in 2D case.

if anyone else would like to see the original file, please post the email!

Far June 21, 2012 08:31

after rotation you need surfaces. And then use auto update

hadikhayyamian June 21, 2012 15:05

Thanks, Far. I will check it out and notify you.

hadikhayyamian July 4, 2012 17:44

Negative Hexa
3 Attachment(s)
Dear Far; thanks for your help. it worked properly,

But I have got new problem; disoriented and negative volume elements!

I have attached my geometry, and my blocking. Although surface quad seems very perfect, when I display Dterminant 3x3x3, it says that there are some negative Hexas. You can see attached figure.

I tried several smoothing strategy, but no one worked well.

I would appreciate if you help me!

diamondx July 4, 2012 18:40

you can use index blocking to filter unnecessary blocks so you can fix elements with ease.
It looks like overlapping blocks. Go to pre-mesh and try update-all. see what it does.
You are always welcome to share your project files... we can help you with it.

hadikhayyamian July 5, 2012 16:54

@ diamondx; Thanks for reply. I did what suggested, nothing changed.

this is my file:

diamondx July 6, 2012 08:47

your problem is edge sizing, you can get rid of those bad element by adjusting it.
I don't know why , but sizing is very small, what type of simulation are you performing on your geometry ? was it on purpose ? if not, start by swtiching from bigeometric to uniform. and select sizing and number of node required... this is how i did to get rid of bad element.

Far July 6, 2012 16:25

Geometry opoerations and some error in blocking
I have reconstructed the geometry completely except few critical curves. Good geometry construction is essential for good meshing.

Here are the files:

There are strange double blockes in files you sent. I can see double blocks with missing vertices in middle

diamondx July 6, 2012 17:05

good job far !

Far July 7, 2012 01:25

Thank-you Diamondx

Here is the difference as pointed out earlier. I don't know why this happened, I have never come across such issues in ICEM.

Far July 7, 2012 05:43

Just improved the meshing in front part. For this i used two step strategy.

Step 1
1. split block into half horizontally.
2. Split blocks at two corner vertically (two splits)
3. merge vertices at one corner.
4. create Y block in the corner region (two circular corners)

step 2.
1. Go to oblock tab
2. Select all blocks and right/left faces and apply.

Far July 7, 2012 07:58

Refer to post #10 and I did not use the Y-block for this case (post #13) in front part. You can combine them later as my aim here is to give you an idea how to improve the mesh and blocking.

As I see you are trying to refine the mesh in boundary layer, which is also main cause of problems in your blocking besides the duplicate blocks are discussed earlier (post #10). So I made the o-grid in the blocks to cater for the boundary layer resolution as shown below. I am also attaching ICEM project files here.

hadikhayyamian July 7, 2012 12:38

Dear Far;
thanks for your effort. I Just found those strange double blocks! it is surprising that when I try to merge them, ICEM displays just one block instead of two blocks.

Also how did you recreate the geometry. did you use third party software like solidworks ... or you used ICEM 's geometry tools?

Again thanks for your reply!

Far July 7, 2012 12:40

I used ICEM geometry tools for geometry operations.

Far July 7, 2012 12:44

I am thinking for the video recording for this case including the geometry recreation operations. Should I? I need at-least 5 likes to make this video and uploaded on YouTube.

hadikhayyamian July 7, 2012 13:00

1 Attachment(s)
@ Far; there is one thing, your hexa also has negative determinant!

Do you know why!

Far July 7, 2012 13:01

let me check. Are u talking about last files ?

Far July 7, 2012 13:11

Files attached in post # 10 have no problems at all. Quality is > 0.6. Files attached in post #13 have this problem, as I did not play with vertices and edges. As my aim was to demonstrate the concept of ogrid-blocking for boundary layer meshing. I try to rectify this blocking and upload it as soon as possible.

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