Visualize air movement in speakers |
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SouthwestCNC
Young Croc Joined: 27 November 2015 Status: Offline Points: 830 |
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Turning the resolution of the sim right down gives you a kind of intermittent flow simulation but yes it doesn't give you a radiation type simulation so really all this could be used for is a rough idea of dispersion through something straight like a horn, sitting a bin in the software and expecting the air to bounce around corners its not going to.
Nastran in cad does however simulate radiation, If you can get your head around it that is. When i have ill upload an image.
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midas
Old Croc Joined: 27 October 2011 Location: Cumbria Status: Offline Points: 2117 |
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This is all very technical.
Is it not as simple as introducing smoke into the box and see what happens? Or into the horn path. Off a cone do you not get the smoke ring effect?
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In bass no one can hear you scream!
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cravings
Old Croc Joined: 30 January 2007 Location: Ireland Status: Offline Points: 7441 |
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But observing the movement of smoke doesn't necessarily have any relationship to how it makes the driver sound...
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SouthwestCNC
Young Croc Joined: 27 November 2015 Status: Offline Points: 830 |
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No i dont think it would tell you anything about how it will sound. One thing it does do is show surface pressures at work. I dont really know if the results of which would have any effects on dispersion or not. Moving air is moving air and i would presume that it would interact to the surface pressures similarly. But drivers push and pull so I really have no idea.
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Teunos
Old Croc Joined: 23 November 2008 Location: The Netherlands Status: Offline Points: 1799 |
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Air by itself does not move as sound passes through it, so no, you are completely wrong, it is by far not the same thing. The usability of these results is completely zero.
Running simulations is something that (unfortunately) almost everybody with a software package can do nowadays. Simulations are however, absolutely purely dependent on what you put in to it. If you supply it with the full momentum and mass balance equations and supply boundary conditions, initial conditions and restraints, you can simulate sound passing through a horn for sure. What you have done is indeed a simulation, and i'm sure its a valid one for the problem that you entered into the simulation. The issue is that what you put into the simulation to start with, has nothing to do with sound. I could steer you in a direction to run valid simulations using your software, but i wont. I wont because i already know, that without proper physical understanding of what you are doing, you will never, ever be able to present simulations of what is going on. There is tools with perfectly applicable results out there already, such as indeed ABEC (Bem, not FEM like your model). But even then, the knowledge and experience needed to present results that represent the physical world, is not something you can learn today and be an expert in tomorrow. There is already so much misinformation on here, please dont expand it by posting random simulations and presenting them as valid. Either that, or go off to learn computational fluid dynamics and come back when you understand it. please note, this is not a personal attack on you or anything so apoligies in advance if thats what it reads like, but misinformation in an already not so very sceintific place, is the last thing i need to see here.
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Best regards,
Teun. |
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SouthwestCNC
Young Croc Joined: 27 November 2015 Status: Offline Points: 830 |
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computational fluid dynamics, Interesting I would have thought simulating fluid flow would have been as useful as simulating air.
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Teunos
Old Croc Joined: 23 November 2008 Location: The Netherlands Status: Offline Points: 1799 |
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Okay, let me try to explain this.
CFD is merely a collecting term for computational fluid dynamical simulations. It can include computational Aeroacoustics, or whatver you like to call it. My point is, that running a simulation without putting in the correct equations, will never result in a correct answer. Lets say i want to calculate the velocity of a car after 10 seconds if it accelerates at a constant rate. If i simulate this with an equation that models gravity, the results will never be correct. Do you understand what i mean? To exagerate a bit just for the fun of it, What you have done is put a car in a wind tunnel, filled it with lava and fired it up at flow speeds of a million miles an hour, to see if the wind in the tunnel is affected by the presence of the car, when you actually want to know how the car will influence sound passing through the windtunnel, when no mean flow at all is present. Edited by Teunos - 06 April 2016 at 2:56pm |
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Best regards,
Teun. |
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MattStolton
Old Croc Joined: 04 September 2010 Location: Walthamstow Status: Offline Points: 4234 |
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Yeah, you are kinda missing the point about what sound is. It is a wave of energy, not a motion of a fluid. The molecues in the air remain fixed on an average point in space, and vibrate forward and back relative to the cone/diaphragm movement. This movement transfers energy to surrounding neighbours, and they move from rest to convey energy to its neighbour. This energy transfer, or propagation, is called a wave. Whilst hydrodynamics and aerodynamics are identical, save for the value of a few constants, such as density of medium, they both deal with motion of bulk amounts of particles, generally over a surface. Wave physics involves no net movement of particles, you are moving energy through a medium. Forget particle physics, you need wave physics - http://hyperphysics.phy-astr.gsu.edu/hbase/sound/soucon.html The last guy to come on here and describe the action of his mid top in terms of "jets of water coming together from multiple hose pipes", was largely derided, and is still taken the piss out of to this day. Admittedly, failing to understand waves was the least of his problem, he had a few other things going on, but I can assure you that there is no net particle movement anywhere near a speaker, unless you drop it. The only wave that also works like a particle, is light (photons), but even then light is mostly in the wave arena. Unless you try and measure it, in which case Schroedinger's cat will eat it first, leaving you with no particle or wave, and a cat somewhat in limbo. Try these: Note in the second one, how the wave propagates along, but the particles remain static around an average position. More wave shizzle here.
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Matt Stolton - Technical Director (!!!) - Wilding Sound Ltd
"Sparkius metiretur vestra" - "Meter Your Mains" |
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SouthwestCNC
Young Croc Joined: 27 November 2015 Status: Offline Points: 830 |
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Thanks yes, Having read a little into it i can see what your saying a modified fluid flow equasion is required which makes more sense.
Anyone have an y experience with comsol 4.4? There is what might be a pretty good tutorial for 3d simulation of aero and pressure acoustics in comsol but until i understand more about i cant say for sure. Edited by SouthwestCNC - 08 April 2016 at 10:52am |
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MattStolton
Old Croc Joined: 04 September 2010 Location: Walthamstow Status: Offline Points: 4234 |
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NO, NO, NO. There is no fluid flow, be it a liquid, gas, solid, plasma, aerosol, aerogel, any of the numerous low temperature states or any other bloody type of particle! You are dealing in energy, being imparted from a vibrating surface, through a stationary medium, to end up in one's lug holes. Typically only 5% of the energy put into the speaker driver is converted into sound waves, but our ears are quite sensitive, or at least, have a very wide dynamic range. Most of the rest is lost as heat, or mechanical vibration of the cabinet, which itself will create sound waves, and slightly warm the environment.... You only need to consider wave propagation (ignoring how the cabinet may modify the speaker diaphragm response and movement) - so forget particle motion. |
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Matt Stolton - Technical Director (!!!) - Wilding Sound Ltd
"Sparkius metiretur vestra" - "Meter Your Mains" |
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toastyghost
The 10,000 Points Club Joined: 09 January 2007 Location: Manchester Status: Offline Points: 10919 |
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The guys who make Klippel do the kind of acoustic simulation software you're thinking about. Using the correct physics. It isn't cheap and is power hungry.
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Aman Gebru
Registered User Joined: 01 February 2014 Location: Delhi Status: Offline Points: 350 |
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Do you want me to design it for you.
It will stop all this fluid particle plasma shit that everyone wants to talk about to make themselves look good. |
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