What TD seems to be talking about is a different (more advanced) way to model a horn. What you do is model the straight sections as waveguides/ducts only, and the bends are modeled as base forces of mass/resistance/compliance, and not waveguide/duct elements.
AkAbak can do it, but getting it right is not easy. My experimental equations for the AcouMass and AcouResistance for one bend are longer than most of the full simple scripts I have posted in this thread.
If you look up those two elements (might as well check out AcouCompliance as well
) in the AkAbak manual it will give you the idea, and base equations. Then you have to figure out how to apply it to bends with changing area, different degree corners, and frequencies. Just so you know the simple 90deg corner mass equation will not work right here, so don't waste your time there.
It is much simpler to just physically account for the path length, and model that way.
Something along the lines of this will give you good results with a horn with multiple bends.
You use each triangle section though the bend as a waveguide element. This will adjust the mass/resistance properties though the bends on it's own, and get it pretty darn close. If you do it correctly the FR and impedance peaks and dips will line up the the true measured ones. The Q of the peaks and dips will be a little different, and will generally be a little less in magnitude as the frequency rises, but you can get a very accurate model without you having to become a PhD level math whiz.EDIT:I should add that this only works at sub frequencies. If you need bandwidth much above 150Hz you will want to learn the hard way. The dimensions through the bends must be less than 1/4WL of the frequencies in question.
Stuffing is also a pain as there are no defined reference points there. No area, rayls/ms or fiber density inputs. The visc numbers are imaginary, so you just have to guess. You could manually input your own code to account for it, but it will not be easy. Here is a link to some math to give you an idea of how to handle it.http://auralization.blogspot.com/?zx=549be658a4a7f370
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