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imanmirzaiian June 23, 2010 08:32

complicated geometry
1 Attachment(s)
hi every body
i,m iman and i am working on a mixer. that geometry is complete in rar file that is problem is that i have no idea how could i blocking this complicated geometry?

imanmirzaiian June 23, 2010 08:34

is there anybody else
:confused::confused::confused: plz help me , i,m waiting online

PSYMN June 24, 2010 11:11

CFD Online isn't really a quick help sort of place... It is more like a "next day or week" sort of place. For more rapid help, you should probably call Tech Support. ;)

But now that I am here, I see that there are problems with the zip folder. I can't extract it. Please check it.

imanmirzaiian July 6, 2010 05:52

hi there
my mistake !!?
about the zip file :with zip extension the size exceeds the limitation(97kb) then i make a rar file and change the extension to zip;););). plz change the extension to rar :D and have a look.
thnk u.

PSYMN July 6, 2010 10:05

4 Attachment(s)
Ok, sure... This model is no problem (but it may be a bit tedious).

If you look from this angle, it is essentially a CGRID with an OGRID in it. From the other two directions, it is just a block with splits. As with many models, there are a variety of ways to handle it.
Attachment 3999

1) You would start by creating a block around the extents and associating it to the outer curves.

2) then split to separate the concentric circles on the left from the Hgrid to the right.

3) then you could view it as a CGRID for the outer layer (select both blocks and face the front, back and right side), and then put an OGrid inside the left block or you could go with a simpler topology and just go with the Ogrid. Here I show the simpler (but lower quality) approach to create an OGrid for the concentric circles.
Attachment 4000

4) once you have your ogrid index, you can split it to capture the various levels such as the circles and the inner and outer (radially) sides of those blocks. Just make sure you leave the HGrid within the center of the circle and don't associate its edges with any circles (or you will have bad angles inside the HGrid block and need to insert another Ogrid. It would still work, but would take another step).

Attachment 4001

5) after associating as many edges as possible from these Ogrids, you could go and take care of the small circles (inlet/outlet?) in the sides of the right block... I will put those pics in a second post since I am limited to 5 pics here.

6) Then after doing all the simpler work and making sure the model is nicely aligned and associated, you can rotate the model sideways and create the splits to capture the side details. By the time you are done this step, you will have quite a lot of blocks and edges to work with, so it is important to do as much associating, etc. as possible before this step... so you don't have to do those things with multiple edges later.

Attachment 4002

7) finish associating, moving, etc. This is the tedious part. Your eyes may start to get confused, so perhaps associate edges right after splitting for them (do steps 6 and 7 iteratively). Also, make sure you know how to use index control to limit your view to just the index planes you are working with. Also, turn off surfaces and blocks, etc. You only need to see edges and curves, keep display clutter to a minimum.

PSYMN July 6, 2010 10:14

Circular inlets
4 Attachment(s)
5) in more detail.

For creating the circles in the HGrid, you have two primary options.

either way, you start by splitting to create a box that is a bit larger than the circles. (usually width of the box is double the diameter of the hole).

Then you can create a single Ogrid thru this block by selecting the block and adding faces on either end. (note: I did this before splitting in the other direction, or I would have a bunch of blocks to select, in that case, use the "from corners" selection so you don't have to pick them one by one.)
Attachment 4003

Here you can see that it creates a new Ogrid index, this can be split to account for the boundary of the circle. Make sure the square Hgrid is within the circle and not associated with the curved sides (other wise the HGrid will be forced to fit to the circle and bad quality will result).
Attachment 4004

The other option is more flexible because it applies to anywhere that you may have a round hole that could create an impingement on the flow... In the perpendicular direction, create an additional split (usually the depth that you expect the jet of flow to penetrate, but here I have made it double the diameter), then select the block and face only the outside.
Attachment 4005

This will give you an Ogrid (CGRID in one direction) that will capture the round inlet and give you lots of extra elements to refine the plume, but without propagating thru your whole model...
Attachment 4006

Best regards,


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