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-   -   [ICEM] Blocking strategy (http://www.cfd-online.com/Forums/ansys-meshing/78455-blocking-strategy.html)

BrolY July 22, 2010 04:46

Blocking strategy
 
Here are some advices from Simon about blocking strategy:
I'm sorry, I can't attached my model, so I just keep the general information.


There are essentially 5 steps to blocking.

1) Split blocks (includes Ogrid Splits for Topology or to improve orthogonality)

2) Delete blocks you don't need (or move blocks to other parts)

3) Associate Blocking to underlying curves, etc.

4) Move blocks into place (includes align, split edges, etc.)

5) Set sizes, etc.

After that it is just about checking the quality and tweaking the blocking to improve quality.

You should go as far as you can thru the five steps as often as possible. In this way, you are handling the model in simplified chunks and it never gets too complicated.

In other words... Rather than split up the whole model and then try to put all the blocks into correct parts, and then going back to associate each edge, and then trying to move each edge into position... How about starting with a few basic splits to capture the largest features. Then if some larger blocks are clearly in one part or another, you can assign them then (or delete them)... Then associated those few edges with any curves (as it makes sense to do so). Then move verts to fit your model... After taking each set of splits as far as possible, go back and work on the next thing. When you do it like that, you are associating edges while you only have a few (ideally when your edge to curve ratio is one to one, rather than after you have many small edges to associate. You are moving a very few verts, rather than many. You are selecting fewer blocks for each operation, etc. It is just much simpler. You will make fewer mistakes and fewer unnecessary splits and when you do make a split between planes that are already aligned with your geometry, the new split will be closer to aligned and require less rework...

That said, you could proceed from where you are (if you really don't want to go back). Go thru using the index control to limit what you are looking at and associate and move some of the major planes... Use "Align Verts" to save you time on the secondary indecies. After you have the model fitting well, you can use OGrids to sort out the orthogonality issues in the curved areas (use Index control to reduce your blocking to just a single tank in X and Z, but keep end to end for Y, in your case, this would actually require some further splits. Then Put OGrid inside with faces on the ends so the OGrid passes thru... I can help again when you get closer to that point. It will probably be worse than starting over though because of all the adjustments you will need to make on so many verts.


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