Acoustic Horn Design – The Easy Way (Ath4)

Hi,

Yes, I realized this just after I released the tool... It's still tangent but curvatures at the joint may be (and will be) different. It's because I forgot to take the OS curvature into account - I just assumed it low enough, which is not allways true - especially near the throat, as you say. I will correct this. The solution is simple - to find the corresponding curvature on the clothoid and make the join at that point (now it's allways the origin of the spiral).

Thanks. At least someone is looking closely ;)
 
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Glad to help. I noticed the issue after adding clothoid termination to my own waveguide generator script since I had made the same assumption that you did. I use a simple iterative algorithm to match the curvature, but I wouldn't be surprised if there's a better way (my math skills are a bit lacking compared to some others here :eek:).
 
What we are talking about here - at the joint (the vertical line) curvatures don't really match. While the spiral begins with zero curvature the OS curvature is not yet near zero. It's quite difficult to notice but it's there.
 

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Your STL file should be in the project's root directory, i.e. "kvmoj". The files under the subdirectory "ABEC_project" are solely for the purpose of simulation - the mesh (.msh) file there corresponds to the STL but has some additional features required by ABEC to run properly.
 
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I'm working on a new way how to construct the mesh (STL and MSH files). It will be no longer of constant angular segments but driven by a required element size and angle change so that the mesh density will be more adapted to the whole surface. That will significantly improve the overall smoothness without an excessive number of triangles near the throat.

I'm also exploring the possibilities of Autodesk Fusion 360 - there's probably a completely different and much better way of constructing the final waveguide surface to work with further. I only have to find some more time to finish.
 
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