CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > ANSYS Meshing & Geometry

[ANSYS Meshing] Increasing number of blocks for parallel computing purposes

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 3, 2012, 19:27
Default Increasing number of blocks for parallel computing purposes
  #1
New Member
 
Ivan
Join Date: Aug 2012
Posts: 22
Rep Power: 13
Ivan is on a distinguished road
Dear friends,
I'm having some troubles in ICEM-CFD with the blocking and I hope you can help me. I'm running a simple geometry of a jet spreading into a coflow (I have the pipe into the domain). Up to now, I have divided the geometry in a small number of blocks. Since, however, i need to start a LES on combustion on that geometry, I need to increase the number of blocks as much as I can in order to split them between a large number of processors and run the case in parallel.

I have started from the geometry I have used up to know (where I have associations between edges and curves - no associations type point or surface) and tried to use the simple split along the axis direction. Nevertheless, after I do this, the grid cells are modified in an improper way, as in the blocks near the border of the block I have splitted, instead of going straight along the axis direction, they contract (approaching each other) in one block and enlarge in the next, like a "sousage".

I have reset all the parameters along the edges equal to each other, but I still have the same problem. I would like to know:

1) If there is an easy way to automatically split the block in sub-blocks without modifying any parameter (I do this just for parallel computation purposes, I do not need to use the new blocks into the geometry);

2) If not, which is a way to do this? Do I have to split each surface of the domain, create many other curves and associate each new edge with these curves?

Thank you!

P.s. I can send images representing the mesh if needed.
Ivan is offline   Reply With Quote

Old   August 6, 2012, 11:12
Default Solution of the posted problem
  #2
New Member
 
Ivan
Join Date: Aug 2012
Posts: 22
Rep Power: 13
Ivan is on a distinguished road
I have solved the problem! I'll write down the solution for who may have this issue in future. Practically I have a circular nozzle into the domain, made by two concentric circles in order to have the lips of the pipe into the domain as well. I used two O-grids, one for each of those (that is, for the internal diameter and for the external diameter). At the outlet, this O-grid is not associated with any circular curve, so it is a square (One border of the same block is at the nozzle exit, and one at the outlet). Now, if the block between the cells near the pipe wall and the outlet is enough long, there is no problem. When, however, I split this block in many blocks (for parallel computation purposes) what happens is that I have a circular block really close to a squared one, since by defeault the O-grid automatically generated by the split are not associated with any curve.

What happens now, is that the two edges of the first cell closer to the pipe wall connect both to the same edge of the next (squared) O-grid, that is to say, a hexa cell degenerate into a tetra cell. This of course affects significantly the solution.

To solve the problem I have created a couple of concentric cirles for each new block-border created and associated them with the respective O-grid by hand (painful, since the blocks are many, but at least the problem is solved!).

Ivan
Ivan is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
computing Nusselt number in a cavity Shoaib FLUENT 1 June 23, 2009 05:22
air bubble is disappear increasing time using vof xujjun CFX 9 June 9, 2009 08:59
[blockMesh] BlockMeshmergePatchPairs hjasak OpenFOAM Meshing & Mesh Conversion 11 August 15, 2008 08:36
Smooth Grid Error! Help seasoul FLUENT 1 March 24, 2008 11:56
Number of CFL and computing time ds2taieb OpenFOAM Running, Solving & CFD 0 March 29, 2006 11:30


All times are GMT -4. The time now is 02:32.