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Mesh quality check for VWT

In the introductory video for VWT , it was specified that even if the mesh quality is bad enough still VWT gives quite a reliable solution for the model we are trying to simulate. But it won't be absolute

I want to ask that which parameters in the quality check of mesh do we have to take care of to get the best simulations of a race car(identical to real life)?

Of these mentioned below in the image file

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ydigit

I would suggest following checks:

- Connectivity

-Duplicates

- Min Angle < 5°

- Length < 0.001 (assuming the model is in meters) This check will highlight all elements less than 1mm length.

1 For surface meshing, you will want to resolve any feature on the vehicle with at least 5-10 elements. So if the feature is 100mm then use a 10mm surface element.

These checks would give you a good surface mesh.

Altair Forum User

Why do you deny using a mesh with small element size? Won't a finer mesh give me better results? I just have a doubt about the length criteria. Why such a limit on smallest length?

ydigit

The reason I avoid very small elements is that, generally it can mean a skewed element.

Fine mesh generally gives a better results. But in CAE world, we have to be practical as well /emoticons/default_wink.png' srcset='/emoticons/wink@2x.png 2x' title=';)' width='20'>

The finer we mesh the more compute resources and time it would require to get a solution.

Altair Forum User

My mesh of the car didn't have min angle>5degree. No duplicates, free edges, penetrations and fully connected but my mesh is not running in VWT. So how do I run them. Very less number of elements are less than 5 degree so it's okay if I get very small errors, it would be very small. But it won't run. So is less than 5 degree a compulsion?

ydigit

No it is not a compulsion to have all elements less than 5 Deg.

Could you send a screenshot of the run folder? Do you see CAD.DIR, MESHSIM.DIR etc folder?

If vwtAnalysis.MeshSim.txt and/or vwtAnalysis.1.Log is generated, please upload.

Altair Forum User

There were intersections. Cured them. What is this msg? Purged 252 lines. Current limit of 100 exceeded.

Altair Forum User

It still shows mesh_intersections dat and nas files. All things are great!

What's the error here?

Unable to find an attachment - read this blog

ydigit

There were intersections. Cured them. What is this msg? Purged 252 lines. Current limit of 100 exceeded.

Could you upload the file that has this error?

A screenshot of your run folder would be also helpful.

ydigit

It still shows mesh_intersections dat and nas files. All things are great!

What's the error here?

This file has only geometry. No mesh.

Unable to find an attachment - read this blog

Altair Forum User

Oh yes. Sorry Y-digit. I found the errors. After I corrected the intersections, free edges arose. Trying to solve them!