thanks for the advice!
yea i am currently working on the squished cells by increasing the distance of the first region refinement level from the geometry.
Test 1.9 has level 9 at 0.001
Test 2.1 has level 9 at 0.005
Test 2.2 has level 9 at 0.01
I have also added decreasing levels as the distance from the geometry increases but im not sure if they are getting overwritten. Im going to finish my report of test 1.9-2.2 and report in a bit
RW Test 1.9
Changes:
| Level 0 (calculated) | 1m |
|---|---|
| Level 1 | 0.5m |
| Level 2 | 0.25m |
| Level 3 | 0.125m |
| Level 4 | 0.0625m |
| Level 5 | 0.03125m |
| Level 6 | 0.015625m |
| Level 7 | 0.0078125m |
| Level 8 | 0.00390625m |
| Level 9 | 0.001953125m |
| Level 10 | 0.0009765625m |
| Level 11 | 0.0004828125m |
| Level 12 | 0.000244140625m |
0.001953m * X = 0.00182182m
0.00182182m /0.001953m = X
X = 0.932
| Inflate boundary layer settings - layer calculation | Y+ Value | |
|---|---|---|
| Layers | 3 | |
| 1st | 0.001078 | Y+ = 50 |
| 2nd | 0.0014014 | |
| 3rd | 0.00182182 | |
| Overall thickness | 0.00430122 | Y+ = 200 = 0.004311 |
| Expansion ratio | 1.3 | |
| Min thickness | 0.001m | |
| Final layer thickness (RATIO) | 0.932 | |
| Relative | 0.932 | |
| Absolute | 0.00182182 |
Results:
Test 1.9 Pic 1: Cell squish between main wing and elements. Not many cells shown of level 9 region refinement at 0.001 - must increase distance from geometry.
Test 1.9 Pic 2: Cells are not even along wing surface - solutions could be adding feature refinement or unequal min max of refinement
Test 1.9 Pic 3: Shown again the surface refinement levels of the wing surface affect the boundary layer cells making unequal cell sizes - no bueno
Test 1.9 Pic 4: Trailing edge gurney flap boundary layer is well meshed
Test 1.9 Pic 5: Trailing edge of 1st element has jagged trailing edge
Test 1.9 Pic 6: Edge of endplate has some odd cells - solution could be unequal min max levels
Test 1.9 Pic 7: Layering chart from the meshing log. Thicknesses are good in some areas but need to be approved in others.
Overall results: Surface and region refinements need work
RW Test 2.0
Changes:
Results:
Test 2.0 Pic 1: Region refinement level 9 is more prevalent even though the distance is not changed. Trailing edge boundary layer cells gone in main wing trailing edge. Squish is reduced slightly
Test 2.0 Pic 2: Gurney flap boundary layers gone, but cell refines to a lower level - most likely to surface refinements moving to lower levels
Test 2.0 Pic 3: Main wing trailing edge has many jaggies even though cell size is reduced near the edge
Test 2.0 Pic 4: Gurney flap has some bad cells
Test 2.0 Pic 5: mesh thickness log shows less coverage then test 1.9 without the feature refinement.
Overall results: Feature refinement allows transition to designated higher level surface refinements to show up. In test 1.9 the higher level trailing edge refinements (especially at the gurney flap) are not recognized
RW Test 2.1
Changes:
Test 2.1 Pic 1: Increased region refinement level 9 to 0.005 gave better results then test 1.9. Increased distance of level 9 did not help with cell squish - solution, maybe this needs to be increased further to conjoin the two regions
Test 2.1 Pic 2: Same as pic 1 Showing how the surface and region refinements are related. It can be seen that in Test 1.9 Pic 1 with a region refinement distance of level 9 at 0.001m away from the geometry, this does not surpass the overall thickness of all three layers which results in 0.0043m This is why the level 9 region refinement doesnât show up well on the mesh clip and seems to go directly to the next lower level 8, which was set at 0.005m. In this picture below the level 9 region refinement distance was changed to 0.005, and level 8 to 0.01m which is why there is better coverage outside of the boundary layer. Understanding that with distance from geometry region refinements, the first level distance value should be larger then the overall thickness of the boundary layer.
Test 2.1 Pic 3: Cell squish is still apparent even with increased level 9 region refinement distance.Also notice that the boundary layers near the trailing edge have disappeared. - solution could be to make unequal min max levels for trailing edges
Test 2.1 Pic 4: Endplate edge cells are better and wing surface cells are also better.
Overall results:
Boundary layer depletion around trailing edge - no good
Cell squish is not gone - solution is to increase the distance of level 9 region refinement
RW Test 2.2
Changes
Test 2.2 Pic 1: Increased level 9 distance did not remove cell squish
Test 2.2 Pic 2: Trailing edge boundary layers gone still between 1st and second element
Test 2.2 Pic 3: Trailing edge has jaggies just like test 1.9. I think the unequal cell sizes on the surface refinement is to blame. Not sure how to fix this
Overall Results: Need to find new solutions to problems
Going though what i have done again. I feel that my attempts to get a really good mesh using different refinement settings might be towards its end. I think if i understood the mesh settings better, especially the snap controls and layer adding controls, i would be able to better manipulative the cells by changing these settings. This is where i need more guidance
Yep, that is why I would likely do this.âŚ
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Would be fixed by squaring off TEs and making sure TE is 0.5mm like I said here:
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That is tough I have same issue on my CyberTruck tire tread, I tried changing all âSnap controlâ parameters but no luck yetâŚ
Donât worry about squish if mesh log does not complain at the end of itâŚ
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My advice now is make the CAD geometry file edits I suggested and try againâŚ
EDIT: When you try again (just in case you are not using âcopy mesh settings fromâ), just make a new sim with the new Geometry, then on âmeshâ dropdown, select âcopy mesh settings fromâ and select the mesh that you like best so far, say 2.2 if that is your best⌠That way your new edited mesh refinements will not overwrite any other mesh⌠I use a new sim for EVERY successful (or error-ed) mesh, I REALLY suggest you continue to do the sameâŚ
Golden rules:
Donât be afraid to go back to CAD and fix regularlyâŚ
I found an OK workaround for the âfloating point exceptionâ issue⌠Support has not come up with anything yet 
Ok dale im going to go back and change the CAD files. It was still worth it to see how everything works together. I have a lot of CAD work to fix on other parts of the car so i will be doing that at the same time. I might be able to have most of it done by tomorrow. Ill do another wing run when im done then hopefully a simulation of that will give me a good Y+ average overt the surface.
I also want to know how you got this measurement tool. Is this within simscale or your own setup?
After that I have to learn the Paraview post processing. So i can make the awesome Y+ histograms. SOO much to do. Ill keep chugging away
Rear Wing 2 Test 1.0
RW 2 Test 1.0 Pic 1: Trailing edges still looking good
RW 2 Test 1.0 Pic 2: Element and gurney flap boundary layers also looking good. Cell squish still an issue
RW 2 Test 1.0 Pic 3: Trailing edges very clean - Dale had it right with CAD geometry being the problem (not surprised he knew this)
RW 2 Test 1.0 Pic 4: Gurney flap also looking very good. Still funky cells on endplate edge though. I am not concerned about this, the wings are most important
RW 2 Test 1.0 Pic 5:
Overall Results: While I am very pleased with these results, and would consider stopping here in terms of overall mesh quality. I would still like to have more understanding and control over certain areas such as:
Surface refinement control
The new problem of mesh squish
Moving onto simulation settings. I am starting to read up on the correct numerics for my situation. I have read through some of your old threads such as Initial Values for turbulence coefficients and continued with the paper from Spalart and Rumsey. I am trying to start at the beginning with understanding the Initial Conditions settings as the FSAE tutorial said to use do the following changes:
Based on my brief reading on these topics, this recommendation from the Spalart and Rumsey paper gave a good explanation.
B. Boundary-Layer Levels, and Device Reynolds Numbers
Another very concrete consideration in aerospace applications is the gap regions between different elements of a wing. These are normally designed to allow a âpotential coreâ between the two boundary layers. It is all too easy to set the ambient νt so high that this potential core is smeared, and to be ignorant of this fact, deeply hidden in the flow field. Yet, this will make CFD inaccurate, and sensitive to ambient values.
A. Free Decay
As mentioned earlier, for large decay rates, the coarseness of the grid far from the body may make the solver unable to support an accurate computation and the decay can be grossly underestimated.
Using significantly lower values for freestream Ď, however, the decay rate is dramatically reduced, and CFD predicts the levels with greater precision on all three grids (lower curves).
III. Ambient Values
We also consider the common situation in which the ambient values are picked to trigger turbulence in all boundary layers without local tripping, except perhaps at very low Reynolds numbers.
C. Recommended Values
the SST model can encounter a particular problem when the ambient value of νt/ν is large and Ď is set too small. The main problem with this erratic behavior is that convergence can stall. Figure 3 suggests that values of Ďc/U up to 100 would be more than safe, so that the useable range is not too narrow.
To summarize, the following ambient freestream turbulence values (in the region near the body) are recommended for general use for most typical external aerodynamic applications with two-equation turbulence models: k/U2 = 1 Ă 10â6 (or Tu near â 0.1%), Îľc/U3 = 4.5 Ă 10â7, Ďc/U = 5. These values yield an ambient eddy viscosity ratio of νt/ν â 2Ă10â7 ĂRec. Thus, for example, for Rec = 10 million, νt/ν â 2; and for Rec = 1 million, νt/ν â 0.2. Again, these ambient levels are not achievable if the turbulence variables are allowed to decay naturally according to the turbulence equations. One easy way to achieve these ambient levels in practice is to impose them as both inflow and floor values.
My (k) value should be be under 3.
My (w) value is should be close to 100 using the K-W SST model.
Am i going too deep into these values? Is this really that important for my results?
Although you squared up your TEs, their thickness is still less than level 11 which is 0.488 mm.
When I said make them 0.5 mm, that was a precise recommendation, specifically because it was greater than the 0.488mm Level 11 size using a 1 meter level 0 gridâŚ
If you make them 0.5 mm, your TEs should get layered all the way aroundâŚ
I am cutting it close here with such little difference (0.012 mm) but it should be enough, it they still donât get layered then you will have to try 0.55mm or the likeâŚ
It is VERY important for all of the geometry features that you want layered to stay above the L11 0.488mm sizeâŚ
And squished cells seem OK when looking at log:
Dale i understand your recommendation to make the TEs exaclty 0.5mm, and know this would help. The problem is the way the CAD is constructed, where each wing profile is an imported sketch that is extruded. If i try and change the TE width, the whole sketch profile will scales, making the wing larger. Im not at all saying there isnt a work around (im pretty good in SW) .
Ill take your word that the squish is ok if the log says its ok. But am i correct that a change in mesh setting values, say non-orthogonality from 70deg to 75deg, will show illegal cells at 70 deg but no illegal cells when its set to 75deg? What i mean by this is that there will still be illegal cells in the mesh, but since the upper limit of the log reporting illegal cells was changed to 75deg that all the once illegal cells are now âokâ and dont show up in the report?
The funky cells were the wavy ones on the endplate edge. I guess there ok
Also did a Sim of the new rear wing
Convergence Plot looks good
Coefficients graph also looks stable
Y+ values (10, 30, 50, 80, 300)
I definitely like your Y+ histogram and ORSI plot but they are your personal creation correct?
You really want to get into it donât you ? 
I am currently working on a huge understanding issue with NonOrtho (and other quality metrics)⌠I am using blueCFD to run OpenFoam on my PC and I am looking at OpenFoam quality metrics, which extend beyond what we see in the logâŚ
For now, my recommendation, even when the relaxed NonOrtho value (set to 75 degrees by default) are used in the log, is that you are still OK in that regardâŚ
NO NO, I really dont haha
I am working on releasing and update with ORSI soon, if you so load the current version that does not have ORSI yet, make sure you switch Windows decimal and thousands separator to â.â and â,â or the histograms fail (just noticed that issue a few days ago, I guess no European people have used it)âŚ
OK now your yPlus plots look like we can consider them, time for celebration 
BUT you have way too much surface area <20⌠Back to drawing board⌠need much thicker 1st layerâŚ
I can easily extract your airfoil curve in Rhino, edit its control points and select the last few control points on say the lower surface near the TE, then rotate those control points around the furthest forward selected control point so that the TE thickness can be changed to any value, with a smooth transition, without rescaling the whole airfoil⌠Then I just extrude that curve to the required spanâŚ
What CAD SW you use?
yes i noticed that, i asssume when i manually change each value of Y+ between 10, 30, 50, etc⌠that each value should be mostly red on the geometry. When i get towards 300 the colors should be giving other values, just as nothing should be red when Y+ is set to under 30
or should it be red under 30 just the upper limit needs to be expanded
Try forum search for yPlusHistogram and download the current version, you can have more control over how you âseeâ your yPlus surface values that wayâŚ
You also need Paraview, but donât worry, I have a video with program that shows how to get csv fileâŚ
But then you will never stop using ParaView 
I can download that NO WAY!
