CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Meshing & Mesh Conversion

How to split this block into smaller bricks

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   July 1, 2008, 09:13
Default HI, I am trying to split th
  #1
Senior Member
 
Pei-Ying Hsieh
Join Date: Mar 2009
Posts: 317
Rep Power: 9
hsieh is on a distinguished road
HI,

I am trying to split this block into smaller bricks with contrains on all 6 faces. I can only add additional nodes inside the block. Can someone shed some light on this?

(all 6 sides are fixed - cannot add more nodes).



Thanks!

Pei
hsieh is offline   Reply With Quote

Old   July 2, 2008, 09:00
Default That is impossible, because se
  #2
bengtsson
Guest
 
Posts: n/a
That is impossible, because several of the surface faces can never be part of a closed hexahedron, if you don't want to subdivide them. (Any four quadriliterals, mutually connected to a quad strip by disjoint edges, would have to form a closed strip, but they don't.)

If you numbered your patches I could explain this in more detail.

What do you mean by "bricks with contrains on all 6 faces", why can you only add nodes inside the block, and why don't you use general polyhedrons?

Ole
  Reply With Quote

Old   July 2, 2008, 17:52
Default Hi, Ole, Thanks for the rep
  #3
Senior Member
 
Pei-Ying Hsieh
Join Date: Mar 2009
Posts: 317
Rep Power: 9
hsieh is on a distinguished road
Hi, Ole,

Thanks for the reply!

This block is part of a much bigger mesh. I am using this block to transition to other blocks with "already" fixed number of nodes. All the nodes on the 6 outer faces of this block are fixed.

The problem is that, this is only an initial mesh. I cannot have polyhedrons in the mesh, only Hex elements are allowed.

I am hoping this is not impossible (but, maybe this is really impossible). I am still giving this much more thoughts. I will post some examples later.

Pei
hsieh is offline   Reply With Quote

Old   July 2, 2008, 18:38
Default Hi Pei! I still don't underst
  #4
bengtsson
Guest
 
Posts: n/a
Hi Pei!
I still don't understand why you impose unnecessary constraints which make a solution impossible. Do you want to use blockmesh independent from Openfoam with a solver which is limited to hex elements?
Any CFD tool that I know, including Openfoam, can easily mesh your structure, if you either
- allow additional nodes on the surface (can be easiliy propagated outside) or
- allow more general elements (a tet mesh is trivial, but requires much more than the minimal 4 elements.)

Maybe you shouldn't ask how to do what you have in mind, but instead ask how to find a solution to your problem. Of course we don't know the problem, so I'm afraid we can't help.

Ole
  Reply With Quote

Old   July 3, 2008, 09:25
Default Hi, Ole, I really appreciat
  #5
Senior Member
 
Pei-Ying Hsieh
Join Date: Mar 2009
Posts: 317
Rep Power: 9
hsieh is on a distinguished road
Hi, Ole,

I really appreciate your help.

Unfortunately, life sometimes is tough. In this project, I am constrained to all hex elements (no tet, no polyhedrons). Also, this is a block using to transition from dense mesh to coarse mesh, hence, all nodes on all 6 sides are fixed (so that the nodes match with its neighbors). Only adding nodes inside the block is allowed. This is where the challenge comes from.

Below are two examples similar to what I am trying to achieve.




Pei
hsieh is offline   Reply With Quote

Old   July 3, 2008, 10:51
Default >This is where the challenge c
  #6
bengtsson
Guest
 
Posts: n/a
>This is where the challenge comes from.

I guess people call it positive thinking if you have no unsolvable problems, but a few challenges instead.

Have fun!
  Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Block Tridiagonal and Block Bidiagonal solver Amit Main CFD Forum 8 February 18, 2015 17:53
problems with viewing mesh block by block James CFX 0 January 22, 2008 13:11
Block-Block tridiagonal matrix inverse Abdulhafid Elfaghi Main CFD Forum 3 September 16, 2007 02:55
RMS Res. is the smaller the best? Anderson T F CFX 10 September 12, 2007 05:59
Can y+ be much smaller than 1 for... Rodrigo Madariaga FLUENT 3 June 7, 2001 23:38


All times are GMT -4. The time now is 08:53.