[france]

Hello All,this is the first time i come here.
I need to extrude a mesh by rotation ,the cross-section shape can look in attachments.Thickness is 8um,i devide it into 2 layers.The two radius are 21.5mm and 36.25mm. So when i extrude the mesh,it have a large number of elements,about 700thousand. And the quality of mesh is poor. the apsect ratio is small than 0.1.
thanks for any friends' help

[Far]

can you show some pics?

[france]

Hi Far,Here i show some pics for you and i give my model in the attachment.i'm very appreciate you can take some minutes look at it.

[kad]

Creating mesh by extrusion is not very suitable in this case, as log as you don't like to end up with very high number of cells. For a reasonable number of cells you will get bad aspect ratio.

Let's do a little math:

- aspect ratio = smallest edge/longest edge, your smallest edge is 0.004 because of the 2 layer thing.
- Worst aspect ratio is to expect on the outer circusphere (length = 227,8mm)
- reasonable mesh size let's say 2 million. Initial mesh has roughly 2000 quads.
- this gives you 1000 layers for the resoltion of the full 360 degrees and a edge length on the outer circumsphere of 0.2278mm. Dividing 0.004 by this value gives you the worst aspect ratio in the domain to 0.018.

An optimum aspect ratio of 1 on the inner circumsphere would correspond to roughly 33700 layers and a cell count of 6.75e07.

Btw. the criterion quality is good when it is near one.

[france]

Hello ,Kad.
I read you reply carefully.I agree with you so much. If using create mesh by extrusion in this case and for good aspect ratio it unavoidable cotain large number elements.But any way can be used to solve my problem.My project must do this case, now,I run into a huge difficulty. I have no idea to solve this problem.I hope someone can give me addvises.
Kad,thanks again for reply.

[kad]

What exactly would you like to do with your model? Please describe it a little more in detail.