Tree preprocessing accelerated with the "Tree Pre" extension

Joshua Pennington

Tree geometry provides a unique challenge to preprocessing due to the relative size of the members; for example, the trunk is rather large compared to the tips of the branches which comes to a fine point. Placing an acceptable mesh – balancing between quality and quantity of the elements – across the model is not a trivial task; for example, the high aspect ratio of the elements can cause solver errors. 

 

While Altair HyperMesh has all the necessary tools to prepare the geometry and generate a quality mesh, it can become time and labor intensive. The solution presented here is the  “Tree Pre” extension – illustrated below – which automates the repetitive tasks and provides a focused and process-oriented toolset. 

 

 

Equally important are is the tips and tricks by which to apply the toolset - summarized below and illustrated with a preprocessing diagram. 

• Save the model at given steps

• This process is optimal for integer scales (e.g. >1 min edge length)

• Trim may be used globally and locally

• After global trim use the stitch tool to isolate trimmed branches and organize into a new component and hide; continue Trim interating

• When using the trim tool globally work up the tree trunk – measure the lower branch edge length first and enter this value in the Find field

• Stitch visualization may be used as a filter to quickly find disconnected topology (e.g. red free edges)

• Bounding surfaces tool will highlight branches were are enclosed

• After converting bounding surfaces to solids, hide solids and delete free floating surfaces – only solids should remain

• Boolean combine in small sections at a time

• Mesh control surface “regions” should be created for the branches

• Values between mesh controls should allow for a “stepping” between parameters (e.g. global min = local max)

• Iterate mesh sizes on a small region to obtain optimal quality and count

 

The diagram illustrates how our high frequency EM solution - Altair FEKO - may integrate into the workflow. Though it isn't a requirement to using the "Tree Pre" toolset, as the preprocessed tree could also be used for other simulations like external CFD.

 

 

A friendly disclaimer that the extension toolset was design and tested in versions 2022 and 2023. As it was QA'd by yours truly, it has not be officially vetted and should be used and enhanced at your discretion. Finally the ribbon contains only the essential tools, so please don't feel locked into the ribbon and explore and use the wealth of other tools in HyperMesh.

Thank you, enjoy and please share your feedback.