|
[Sponsors] |
November 28, 2016, 07:46 |
Two microphone impedance tube
|
#1 |
New Member
Hannes
Join Date: Oct 2016
Posts: 6
Rep Power: 9 |
Hello!
I am trying to simulate a impedance tube in Fluent with an inlet, then 2 measuring points, an absorbing sample and lastly a rigid wall. The arrangement can be seen here: http://www.scielo.br/img/revistas/jb...1/a11fig01.jpg The idea is to measure the difference between amplitude and phase of the incident and reflected wave. There are a few things I am not sure about though. 1. Will there be errors if I dont have an outlet, just a velocity inlet? 2. If I specify a wall with zero shear at the end (termination) wall, will the incident wave be 100% reflected or do I need other conditions? Can there be any other issues? Thanks in advance! |
|
November 28, 2016, 16:05 |
|
#2 |
Senior Member
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,654
Rep Power: 65 |
You are good to go.
1. You should only have an inlet. That's the real physical geometry in an impedance tube. You should be aware though that for unsteady simulations, there are acoustic boundary conditions at the inlet that may not be so obvious. 2. Slip versus no-slip at the wall really doesn't do anything. What's important is the kinematic blocking of the wall (the wall normal boundary condition, which is simply a wall). The acoustic boundary layer has some cute results but this really isn't a viscous flow problem and even a laminar or inviscid simulation will get you most of the information you need. Unless...you have really exotic conditions with acoustically generated turbulence. However, do not be surprised if the wave is not 100% reflected. In order to have 100% reflection, you would need to generate a perfect plane wave (which is already tricky) and it would need to be reflected completely in-phase. Then there's damping/attenuation, unless you are running an inviscid simulation. |
|
May 15, 2020, 09:06 |
|
#3 | |
New Member
Nick
Join Date: May 2020
Posts: 1
Rep Power: 0 |
Quote:
Also, I noticed what wave depends on the quality of speakers that you using for generating sound. Personally, I using now 6x9 speakers for this experience. I found a good website with a detailed description of them named Audio direct. I found this site occasionally when I was searching to replace for my old microphone, I found their best budget microphone top. Check this out, maybe you will find something useful for yourself. Last edited by Gefest; May 25, 2020 at 21:45. |
||
May 15, 2020, 15:05 |
|
#4 |
New Member
Nick
Join Date: May 2020
Posts: 1
Rep Power: 0 |
||
May 15, 2020, 17:14 |
|
#5 |
Senior Member
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,654
Rep Power: 65 |
The plane wave is generated by using a velocity inlet or pressure inlet. That part is straightforward. The issues come after...
|
|
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
double tube heat exchanger | mehyan | CFX | 4 | December 8, 2015 17:44 |
Pressure in impedance tube | nnis09 | Fluent Multiphase | 0 | March 27, 2014 04:35 |
[OpenFOAM] Tube filter in Paraview | werweisswas | ParaView | 0 | December 10, 2012 07:18 |
[Other] How to set up a dynamic mesh for a piston moving through a tube of variable diameter? | karkar | OpenFOAM Meshing & Mesh Conversion | 0 | July 4, 2012 07:54 |
Simulation of impedance tube (pls help) | khoodav | FLUENT | 0 | February 26, 2011 16:47 |