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 siw February 1, 2013 11:04

Expanding and constant node distribution

Hi,

In Hexa is it possible to set an edge node distribution by setting a first node height, expansion ratio and the max size, so that once the cells have grown from the first node height to the max size the remaining nodes have the same max size? Rather than continuing to grow.

I thought that by setting a value in Pre-Mesh Params > Edge Params > Max Space would do that but instead it just increased the node quanity and reduced the first node height.

I was wanting to avoid splitting up blocks and setting their own edge parameters in order to get this as I would have to off-line calculate the location of the largest grown node to make a split to the set the sizings for the constant size node spacings.

I hope this is a clear explanation. Thanks.

 energy382 February 4, 2013 10:42

Quote:
 Originally Posted by siw (Post 405517) Hi, In Hexa is it possible to set an edge node distribution by setting a first node height, expansion ratio and the max size, so that once the cells have grown from the first node height to the max size the remaining nodes have the same max size? Rather than continuing to grow. I thought that by setting a value in Pre-Mesh Params > Edge Params > Max Space would do that but instead it just increased the node quanity and reduced the first node height. I was wanting to avoid splitting up blocks and setting their own edge parameters in order to get this as I would have to off-line calculate the location of the largest grown node to make a split to the set the sizings for the constant size node spacings. I hope this is a clear explanation. Thanks.

you can determinate a mesh law (i usually use hyperbolic to resolve boundary layer) and than either copy to all parallel edges or even selected edges. you can copy parameters absolute, which is important, if you want to achieve y+ <11,6 or relative (to edge length).

so no need to do any splits. for example: if i mesh a turbine blade (single passage), i normally use hyperbolic mesh law for the smaller edges on the hub and bigeometric on the shroud (same index).

so just set your spacing 1 (initial height), ratio 1 and add as many nodes as needed to achieve the max. spacing, you want.

 siw February 4, 2013 14:47

Perhaps I was not clear enough in my desciption.

See this youtube video by Pointwise (http://www.youtube.com/watch?v=uz661XzE1QE) and at about 5mins 30secs they talk about node distribution along an edge with a growth region and a non-growth region. BTW, the whole video is interesting, particularly for me as I used the same CAD geometry for my MSc in CFD research project.

Anyway, what I want to know is how to do this in ICEM Hexa without the need to make a blocking split. Because as far as I understand ICEM cannot do this so I think two separate blocks would be required for the growth region and the non-growth region. Therefore, in order to make the split in the correct place I would have to calculate outside of ICEM where the position would be between the growth and non-growth regions.

Hope that is now better explained.

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