I have a problem with very low mesh quality, even if I use a couple of region refinements and local element size features. I’ve tried to see where the quality is low (high aspect ratio, non-ortho, etc.), but the mesh quality tool is not showing to me this info as it suppose to do (via Mesh Quality | Mesh Visualization Tips | SimScale). So can I ask you to help me increase the mesh quality? Maybe I should somehow edit the CAD, maybe something else I haven’t figured out?
Firstly, mesh quality tool will take some time to display any parameter since the current mesh configuration consists of 22 million cells. I would recommend you to create iso-volumes in the meshing tool by setting high limits for aspect ratio and non-orthogonality (for non-orthogonality let’s say a value between 88 to 89) and inspect the bad quality cells.
Here I have some general recommendations for your mesh and simulation setup as well:
-I’d always start with a simpler and coarser mesh settings. Current mesh consists of 22 million elements which will consume lot’s of core hours during simulation. Start with a coarser mesh and then refine your mesh step-by-step by adding region or surface refinements.
-I believe your boundary layer mesh settings are set to enhance a y+ value of 1 although your wall boundary conditions are set to wall function approach. Unlike full resolution methodology, wall functions don’t require a y+ value of 1.
-Transition from the latest boundary layer cell to the core cells doesn’t seem great. Please try to keep the volume ratio between these cells as minimum as possible. This can be controlles by either changing the boundary layer total thickness or number of layers.
Thank you so much for the helpful tips, I’ll try to improve the mesh quality using your technique. Regarding the y+ and wall function: I ignored this for a long time, while trying to keep y+ at <= 1, but now I realized that I needed to select the “full resolution” option.
Unfortunately, no matter how I tried, I couldn’t improve the quality of the mesh significantly. The problem occurs on the edges of the flaps and I don’t know what to do about it. Finer local surface refinement gives lower quality mesh, which surprises me. What should I do differently?
Thank you very much for the advice, it really helped, the quality of the mesh has increased significantly, but there’re still a couple of flaws. What can it be caused by?
Hello @kamilakas , now that you have tickened the trailing edges, surface meshes should be fine enough here so that good quality elements can be generated. I think applying a surface refinement to these trailing edge faces would increase the mesh quality even further.
I noticed that you tried to run some cases which diverged.
It seems like most of these cases diverge at the tire contact with the streets.
I would suggest to ad a tire patch so that the tire and the street do not come into contact with tangent, but rather have a clear edge to it. This can only be a few mm high, but this should help to improve the mesh in this region.
