Very thin boundary layers and y+ on complex geometry

[jhartung]

I believe that is the % of cells out of the original “perfect” BL extrusion that it is going to retain after doing displacement and applying the quality metrics. You’ll see that number go down with each iteration.

[DaleKramer]

But I think that is just an assumption right now.

I think my calculation (sum of (faces*layers/face))/(total faces) is the correct weighted average of layers/face for all chart data.

EDIT: More research tells my gut that your new discovery is not what you think it is, more to do with individual iterations of layering process, not end result (but I could be wrong)

[jhartung]

No doubt yours is a better metric, but this one is free and fast.

[DaleKramer]

Can’t resist this one… maybe you get what you pay for here

[DaleKramer]

@jhartung , wow this is now the 5th longest thread ever in the SimScale environment with respect to # of posts (I think) …

You deserve some sort of reward for hanging in there

I have learned a lot and I hope you do summarize what you have learned at the end here, so that those who follow may be pointed to the end post because I don’t think that a lot of others will get through the whole thing (but I know I would if I happened upon it )

If you do summarize here, please be sure to edit your 1st post with BOLD text that links to the end summary post

But, be ready for some continuation after that summary

[jousefm]

Good idea Dale!

I think Josh wanted to write a summary anyway once he finished his studies

Best,

Jousef

[jhartung]

Hey all, sorry for the radio silence. Having gotten to some results I mostly like, I had to do some work on the project actually using them. I’ll be back to transform this into a great project and post, fear not!

[DaleKramer]

@Get_Barried

Absolute tolerance 1e-15? That seems way overkill.

@Get_Barried AHA, I finally found Dylans explanation that I think sortof relates to the Absolute tolerance 1e-15 and for sure, the larger relative tolerances that I use, basically for quicker convergence in steady state analysis’s :

@dylan

It is very useful to use a large relative tolerance in steady state, because in this case it is the initial residuals at the start of each SIMPLE loop (time step) that matter, rather than the final residuals at the end of those loops. With a large relative tolerance, the solve will then quickly move onto a newer SIMPLE loop and therefore the initial residuals will drop more ( with more iterations ). The same outcome can be achieved by limiting max number of iterations within each loop.

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EDIT on 11-2-2023: The project where this WHOLE topic is mostly summarized is located here: 'Crop duster lateral stability' simulation project by jhartung
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