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MGabr September 20, 2013 11:53

How to study noise in CFX
Dear all
Could you help my in how to study the noise generated in piping system containing orifice from induced vibration due to turbulence using CFX. I am working with SST model.

best regards

ghorrocks September 21, 2013 06:21

What do you want to know about the noise? Are you looking for a full acoustics simulation (giving frequencies, acoustic dipoles and all that) or just a general idea if it is noisy or not?

MGabr September 26, 2013 01:35

Hi ghorrocks , thanks for your reply. I want to study the noise generated from turblance in order to optimize orifice design for low noise pressure reduction. this would require the frequencsies of waves generated due to pressure pulsation. But at first I want to know if this design is noisy or no. after that I may enter little bit deep study one of them.

ghorrocks September 26, 2013 01:52

Getting the full acoustics spectrum from CFX is difficult - You are going to need to do LES to get that. You can get simple estimates from simple turbulence models and looking at the turbulent energy, but accurate data will require LES.

MGabr September 26, 2013 02:51

So ghorrocks , Which factors should I depend on in my preliminary study and comparing orifice designs using current turbulence model SST . and should I make it transient simulation or I can continue using steady state simulation

ghorrocks September 26, 2013 06:23

You could infer noise level from turbulence intensity on a steady state model. But be aware that this is a very crude guide only. The only way you are going to get accurate results from this is by a LES model, and that is quite an undertaking.

MGabr October 1, 2013 14:53

Dear ghorrocks.
I found That using LES model can't happen in steady state and require transient. Could you illustrate how to inspect the turbulence in steady state , I wouldn't go deeply in studding noise , only need indicator that this design would be better in generating noise due to turbulence.

ghorrocks October 1, 2013 20:41

Just a rough guess that turbulence intensity is linked to noise. So look at the turbulence intensity.

But you really should do some literature review on this to find the most appropriate way forwards.

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