[gambiss]

Hi

I am having trouble making a boundary layer around an aerofoil as I want a y+ as 1 so structure mesh at first (1% of the chord) then unstructure out from that (modelling a VAWT turbine with three blades).

Does anyone have any suggestion how to do this, as when I try it boundary layer function does go around the blade, and just make lines across it.

Thanks

[-mAx-]

first mesh edges from your airfoil

[gambiss]

Cheers. Now when I try to mesh, I either get error: boundary layer is to high, then when I reduce it says: that mesh is not possible without interference.

I have taken off the auto smooth default. Is their anything else I should do?

Thanks

[-mAx-]

can you post a picture with the BL you try to attach

[gambiss]

Still having problems, is this a fault of my meshed edge or? An gambit error, as some times it seems to work with out hassle... and see that other people are having simular problem...

https://picasaweb.google.com/1157392...56072322986802
https://picasaweb.google.com/1157392...56075170157810
https://picasaweb.google.com/1157392...56075170157810

Thanks for you help in advance!

[-mAx-]

if you deselect the trailing edge in the BL-surface list, does the error remain?

[gambiss]

If you mean, not creating a boundary layer around the trailing edge then no, this doesn't work either!

But unsure of what you mean!

[-mAx-]

no I mean, don't pick the trailing edge, when you select edges where the BL will be attached.
Does the error remain?

Originally Posted by gambiss

Now when I try to mesh, I either get error: boundary layer is to high, then when I reduce it says: that mesh is not possible without interference. Thanks

[gambiss]

Yes, now it will mesh, is there any way to get it create a boundary layer around the whole blade?

Thanks!

[-mAx-]

ok that means the error comes from this edge.
Try to add more nodes on this edge.
If it don't help, try to merge the edge with the 2 others (both sides), and perturb nodes distribution

[gambiss]

I've managed to Mesh it now, but, it is really skewed next to the blade, is this just from the position of the nodes and is the only way to solve this adjusting them?

Or is there a simpler way!?

Thanks for all you help, I really appreciate it!

[-mAx-]

post a picture

[gambiss]

https://picasaweb.google.com/1157392...56384960415330

https://picasaweb.google.com/1157392...56392982700834

[-mAx-]

something is weird.
Can you provide me the dbs file?

[gambiss]

http://www.fileswap.com/dl/eQjBziUI/...again.zip.html

[-mAx-]

ok I kept the parameters from your BL and your SF.
But first, you absolutely need to split your domain into several smallest surfaces.
Indeed you have 3 airfoils, so I would isolate each airfoil with a split (circle in my example)
Then Gambit will have less difficulty to mesh surfaces, especially when you impose a thin BL.
So I meshed one airfoil with this method (you choosed tri), but here you can easily mesh it with hexa.
I would mesh it with hexa ,then you can have more control on the aspect ratio between last cell layer from your BL and cells outside the BL.
Sans titre.jpgSans titre2.pngSans titre3.jpg

[gambiss]

Okay, thanks for that! I will reduce my surfaces...

But- I can only select hexa in volume meshing? How do I do it for 2D? :?

[-mAx-]

quad or map

[gambiss]

Hmm, I've meshing the blades seperately but I still get the same skewed BL around them...

[-mAx-]

with quad or tri?
As you saw, with tri I didn't have any problem
post pictures