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Collapsing Prism Layers

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Old   April 24, 2020, 06:49
Default Collapsing Prism Layers
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Hi there, I'm relatively new to Star CCm and am having trouble with some collapsing prism layers (See image attached). I have three separate surface controls for the wing (left), hinge (central) and fan (right), each with custom prism layer first cell heights according to their local Re number and custom number of layers.

Should I adjust these controls to all have the same prism layer settings to avoid this collapsing issue? Its quite a key area of interest to my results. Any help appreciated.
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Old   May 28, 2020, 14:59
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Hello,

I'm not very experienced with surface controls yet I did experience this issue before. The problem generally lies within the prism layer total thickness and stretching. Try to either reduce the number of prism layer, or the above mentioned parameters. Though, if you reduce the prism layer number, you can adjust your stretching and thickness accordingly. Perhaps the best approach here is to reduce the total thickness.

If you are still having troubles switch to one surface control only for all surfaces and see if that makes a smooth mesh.

What I generally do is start with a very coarse mesh and adjust my prism layers accordingly. (Trial and error=D) Of course, it is always better to know the theory behind to obtain a good mesh to save time.

Good luck and have fun =).

Best regards...
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Old   June 2, 2020, 11:59
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Play around with minimum thickness percentage and layer reduction percentage in the prism layer mesher settings. You should be able to hold a better mesh around those corners, however, dropping some layers around a bend like that is not bad practice.

In my experience, trying to tailor local prism is a scale of diminishing returns. Depending on your turbulence and wall model, 1<y+5 and 30<y+<60 with the default all wall model is the sweet spot, but anything between 1 and 100 you ought to get good results.

Don't spend too much energy chasing down the y+ dragon, just get it into range and move on unless you have very specific reasons to dwell on it.
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