Meshing Philosophy: Automated or Automatic?

We like to say our meshing software is automated, not automatic.

What is the distinction?

The ultimate goal of automatic mesh generation is one button push to get a mesh. In this approach, every step of the mesh generation process is automated. The software determines what regions to mesh, how much to resolve different geometric features and areas of the flow domain, and the type of mesh to use. This approach is really, really nice when it works. (Amazingly, it always works during software demos!)

But it has some severe drawbacks for real-world CFD applications. What do you do when an automatic mesh generator fails to produce a mesh? Push the button again? Most likely you will have to make changes to your geometry to get the mesher to work, so you are no longer modeling the real geometry. If you have to make large changes to the geometry, then you will be making large changes to the CFD results you get.

What if the automatic mesher makes a mesh, but it is suboptimal? Maybe it does not resolve an area where you know there is going to be some interesting flow feature, or maybe it has automatically modified the geometry itself in order to successfully create a mesh. (Will it even give you the diagnostic tools necessary to determine this?)

Because the philosophy of automatic meshing is to completely relieve you of the burden of meshing, you are left with no tools for fixing the problems that inevitably arise.

Contrast that with the approach of automated meshing. In this approach, we automate as much of the meshing process as possible, but we keep around the manual tools needed when the automation breaks down or makes a suboptimal mesh. We automate the entire meshing process for some specialized cases. For more general cases, we automate the labor intensive steps in the mesh generation process while still giving you control over the mesh.

For certain classes of problems, like turbomachinery flow paths, we automate the entire meshing process using Glyph scripting. Scripting can also be used to automate repetitive parts of the meshing process that are common to many problems. See the Glyph Script Exchange for examples.

Pointwise contains many automated meshing tools in addition to its scripting language. An example is its automated block and domain assembly. One of the labor intensive steps in mesh generation is defining blocks and domains. (Domain is our terminology for surface grid.) In Pointwise, you only need to define a minimal set of grid curves, domains, or some combination of curves and domains, and it will complete the block or blocks for you.

This shown in the image below, where four grid curves and two domains have been selected (highlighted in white in the left picture) then using the Assemble Blocks toolbar button (middle picture) to tell Pointwise to automatically create any missing domains and assemble the resulting surface grids into a block (shown in blue in the right picture).

 

Automated block assembly in Pointwise.
Pointwise completes the missing surface grids and assembles them into a block.

Pointwise still includes manual block assembly tools, so if you have an unusual block topology and the automated approach did not give you the block you wanted, you can still create the exact block you want manually.

That is what we mean by automated and not automatic. We provide automated tools for many steps in the meshing process and for the complete process in some cases, but we also include the manual tools you need to get the mesh you want if the automation does not give you what you want.

Maybe automated and automatic are not too linguistically different, but in the mesh generation world it can be the difference between getting your job done and being stuck without a solution.

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2 Responses to Meshing Philosophy: Automated or Automatic?

  1. Pingback: Tweets that mention Meshing Philosophy: Automated or Automatic? | Another Fine Mesh -- Topsy.com

  2. Pingback: Reliable Meshing Process vs. Push Button Mesher | Another Fine Mesh

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