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October 13, 2009, 05:16 
[ICEM] Bunching nodes along a curve

#1 
Senior Member
Stuart
Join Date: Jul 2009
Location: Portsmouth, England
Posts: 472
Rep Power: 15 
Hi,
In the Curve Mesh Setup I have been trying different Bunching Laws and values in the Spacing and Ratio boxes to try and get nodes to bunch together at the centre of a curve. But all my attempts result in node bunching at the curve ends. For example: curve with 100 nodes, Bunching law = BiGeometric, Spacing 1 = Spacing 2 = 0.001 and Ratio 1 = Ratio 2 = 2 gives bunching at the curve ends. So I changed the Ratio 1,2 = 0.5 thinking that would reverse the bunching direction but I it didn't. So how can this be done? Thanks. 

October 14, 2009, 13:51 
Bieponential

#2 
Retired from CFD Online
Simon Pereira
Join Date: Mar 2009
Location: Ann Arbor, MI
Posts: 2,660
Blog Entries: 1
Rep Power: 38 
I just tried it and see what you mean about the BiGeometric not working in that way... It seems like it just goes to uniform if you try it...
But the Biexponetial, Hyperbolic and Poisson each worked for me. In my case, I had a curve about 100 units long with size 5 uniform, I set the spacing 1 and 2 to 20 and the ratio 1 and 2 to 0.5... It clearly biased toward the middle at a rate of 2 to 1... I should note that I rarely use this method... If I am going to play with things like this, I would rather use the 2D hexa blocking stuff and just have unstructured patches. 

October 14, 2009, 15:55 

#3 
Senior Member
Stuart
Join Date: Jul 2009
Location: Portsmouth, England
Posts: 472
Rep Power: 15 
Thanks again, I'll give that a try when I get back to my CFD PC.
Trying the appropriate bunching methods seems a bit hitanmiss at the moment. Can the equations be given to maybe get a better understanding and see what parameters are used for each method? For example, in one instance I have a curve and I'd like the extreme lefthand and righthand elements to be particular sizes but not sure what method or values of ratio(s) etc needed, without trialanderror. Although you'd rather use the Hexa blocking, spare a thought for us poor souls who only have tetra/prism . 

October 14, 2009, 15:58 

#4 
Super Moderator
Ryne Whitehill
Join Date: Aug 2009
Posts: 313
Rep Power: 10 
I was having the same issue, ICEM seemed to always force the RATIO=2 on me.
I ended up using biexponential to distribute my nodes As to the equations, see the help guide. It has all the equations in it 

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