Well it seems obvious to me now that even the 0th mode is actually affected by forming the separated channels where each wave develops on its own, within its own boundaries. As a whole it's not the same as a single wave inside an OS waveguide where the wavefronts "communicate" and sum continuously accross the whole internal volume as they develop.
I agree, the ripple tank sims have not looked correct to me from the beginning. Consider some of the earlier plots. They show that the outer ring of sound is moving much faster than the inner one. How is that possible? Sound travels at only one speed, not a speed dependent on which channel it's in.
The radiated sims that you do with ATH, do seem plausible to me. Not much happens until an HOM appears and then everything changes. But note that the cut-ion of this mode has moved to 15 kHz which is almost double its frequency without the vanes.
Something in the ripple tank app does not seem to me to be correct.
I created a ticket for this issue: sound wave propagation speed issue * Issue #4 * pfalstad/ripplegl * GitHub
Maybe authors could fix it.
Well this particular picture was taken already some time after a reflection off the end of the vane (due to an apparent impedance mismatch). So there's already more than one direction of the proceeding waves.
What's difficult to reconcile for me is that there should be different speeds on both sides of the same vane boundary because the path lengths are virtually equal. But who am I to say that it's not possible
I can only see that the wavefronts from all the vanes will not match each other at the end of the vanes - that seems obvious to me.
What's difficult to reconcile for me is that there should be different speeds on both sides of the same vane boundary because the path lengths are virtually equal. But who am I to say that it's not possible
I can only see that the wavefronts from all the vanes will not match each other at the end of the vanes - that seems obvious to me.
No, because the foam works in volume, whereas ABEC is a boundary element solver, i.e. it can't simulate attenuation of the sound propagating through the medium...
Can you provide a definition with multiple longer vanes please? I guess this could demonstrate the issue better than the original example.
Sure -
Code:
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