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-   -   Aeroacoustics - Flow over Cylinder (http://www.cfd-online.com/Forums/main/5030-aeroacoustics-flow-over-cylinder.html)

Axel Rohde August 13, 2002 10:57

Aeroacoustics - Flow over Cylinder
 
I am looking for aeroacoustics papers that deal with the DIRECT computation of sound from the unsteady flow over a circular cylinder (due to vortex shedding). By 'direct' I mean the acoustic pressure away from the cylinder is computed as part of the CFD simulation and NOT through an acoustic analogy approach (Lighthill, etc.). Such a problem was proposed for the Second Computational Aeroacoustics Workshop on Benchmark Problems in 1996. Back then nobody even attempted a direct computation, because it is very expensive. I am trying to find out if somebody has solved this problem ever since.

I have combed through the web, and the only 'recent' reference I have found on the subject is the one below. Does anybody have this paper (PDF) and can email it to me? Does anybody know the authors or know how to contact them? Alternatively, does anybody know of any other attempts that have been made on the subject matter? - Thanks for your help!

Numerical Simulation of Sound Generation by Flow Past a Cylinder AIAA Paper 98-2208 (AIAA Accession number 30806)

San-Yih Lin, Bae-Yih Hwung, and Sheng-Yu Wen (National Cheng Kung Univ., Hsinchu, Taiwan) 4th AIAA/CEAS Aeroacoustics Conference (19th AIAA Aeroacoustics Conference) Toulouse, France, June 2-4, 1998, Collection of Technical Papers. Pt. 1 (A98-30801 07-71)

Dimitri Nicolopoulos August 14, 2002 04:38

Re: Aeroacoustics - Flow over Cylinder
 
You can have a look at our website www.mcube.fr under the M-Explicit/Validation/Aero-Acoustics section. We performed a kato cylinder simulation. There are quite a few other examples and published papers about direct aero-acoustics simulation in the M3/Publications section.

Dimitri

Axel Rohde August 17, 2002 12:18

Re: Aeroacoustics - Flow over Cylinder
 
Dimitri,

Thank you for your feedback. I have visited your site, and I am very impressed by your and your colleagues' work. I have read your paper "Explicit schemes applied to Aeroacoustic simulations", and it answered some fundamental questions I had about aeroacoustics. I am still fairly new to the subject.

I have a few questions if you don't mind in reference to your cylinder simulation, "Turbulent Wake of a Cylinder - M-Explicit",

www.mcube.fr/M-Explicit/validation/val_frame.html > Aeroacoustics

Your virtual microphone is located 1m from the cylinder it says. So I assume the outer boundary to your mesh is of 1m circular diameter? Or do you leave a few flow cells between the microphone location and the outer boundary? What is the diameter of the cylinder? I could not find that on the page. Did you publish a paper on that subject you could send me?

What software are you using for your FFT and SPL analysis, or which software can you recommend? I assume you use narrow-banding in your SPL analysis judging from the graph. What is your experience with 1/3 octave banding? Octave banding seems to make the graph less 'noisy', but I have the impression that some frequency content gets 'washed out'.

By any chance, do you have a PDF copy of the following paper listed in your publications sections that you could email me,

C. Kato, A.Lida, Y.Takano, H.Fujita and M. Ikegawa "Numerical Prediction of Aerodynamic Noise Radiated from Low Mach Number Turbulent Wake" in AIAA 93-1045

Thanks for all your help. It is greatly appreciated!

Axel



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