[thanat]

Originally Posted by guanjiang.chen

Hi thanat,



After simulation finished, you can find the result in the acousticData folder. For each observer, there is a file which has Freq, p', spl. just drawing it is OK. What makes me confused is that the spl in the file shows a symmetry distribution in the frequency range.



Regards,

Guanjiang

IMG_0182.jpg is it gonna be like this one?
Also,what does this code really mean.
IMG_1616046182.146886.jpg
In the line which contains the cod "fftFreq 1024"

[guanjiang.chen]

Originally Posted by thanat

Attachment 83387 is it gonna be like this one?
Also,what does this code really mean.
Attachment 83388
In the line which contains the cod "fftFreq 1024"

Hi thanat,

I don't know the first picture you show is from which case. It seems to be the spl result. The spl I got is similar.

I also want to know what the fftFreq means. I think it is a variable for the fft process. As I calculated the spl using my own code, I didn't focus on this number too much. Also, I tried different values for the fftFreq, the results didn't change. If you get the exact answer, please tell me.

Regards,
Guanjiang

[thanat]

Originally Posted by guanjiang.chen

Hi thanat,



I don't know the first picture you show is from which case. It seems to be the spl result. The spl I got is similar.



I also want to know what the fftFreq means. I think it is a variable for the fft process. As I calculated the spl using my own code, I didn't focus on this number too much. Also, I tried different values for the fftFreq, the results didn't change. If you get the exact answer, please tell me.



Regards,

Guanjiang

OH can I have your setting pls. I would be great for me. Pheethanat1433@gmail.com
Thanks in advance

[guanjiang.chen]

Hi, I have put my settings in the first page of this thread.

[thanat]

oh thanks, And what is your blockmesh dimension and also the setting in 0 and constant file.
I just want to validate with your result shown earlier. i cannot get the result like you with my setting maybe it is about the observer location i set.

[guanjiang.chen]

https://github.com/unicfdlab/Trainin...cs-OF4.1/cases
https://github.com/unicfdlab/libAcou.../Tutorials-4.1

What I show is from tutorials. I recommend you run the FFWH+cfdbem_3D.

[thanat]

Now, In this time,i just dont want to use BEM for some reasons. I will try it.

[guanjiang.chen]

You can delete the BEM set. just run the curle and fwh.

[thanat]

Can i see your blockMesh of the cylinder,also velocity and turbulence setting.

[guanjiang.chen]

I use ICEM to draw the mesh, and use fluent3DMeshToFoam to import the mesh to Openfoam.

[thanat]

Also, is there any functions to use hanning window in the lib?

[guanjiang.chen]

Originally Posted by thanat

Also, is there any functions to use hanning window in the lib?

It may be related to the fftFreq. The code of fft process may be in the FoamFftwDriver.C or AcousticAnalogy.C files. You can also use pwelch function in matlab.

[thanat]

Can i parallel run AcousticLib

[guanjiang.chen]

Originally Posted by thanat

Can i parallel run AcousticLib

Yes, in the same ways you run other parallel cases.

[mortezahdr]

I am trying to visualize pressure fluctuation and/or sound pressure level in the flow field on a slice or a surface. As the grid has 8 million volume cells, if I put more than 600 microphones, the solver crashes due to memory limitation. What parameters can be used to visualize the source of the noise?
I have got the contour of dp/dt, but since I am using sliding mesh, it shows weird distribution inside the rotating block of the propeller as shown below. Is there any alternative ideas for visualizing the sound wave? Divergence of velocity also does not represent anything.

[chakshu]

Hello Guys,

I am bit naïve in computational aeroacoustics. I found libAcoustic library for propagation of acoustic waves.

I am interested in calculating the acoustic signature of a uav propeller. Currently, for aerodynamics I was using steady MRF simulations to get thrust and torque. Further, I would like to study the acoustics using openFoam with the help of FWH - libacoustics. I have some questions as listed below, it would be great if you could help me.

1. Can I use steady RANS to obtain tonal components with libacoustics?
2. What additional things I can utilize with respect to acoustics if I use URANS simulation?
3. Lets say I run a simulation with Hybrid LES + URANS, and I obtain the unsteady pressure distribution. What are the next steps/or (steps before setting up the simulation) with respect to acoustics. I read in some paper where they define FWH surface around a propeller and use FWH libacoustics to get the SPL. How do we define these surfaces, is it a part of mesh? and What is the role of this surface (is it kind of mapping the pressure fluctutation on the surface) ?
4. Also, with hybrid LES+RANS, is it possible capture the broadband noise using libacoustics?
5. As far as I understood, libacoustics is a kind of post-processing utility, I believe I don't need to make any specific changes to my mesh to use it, correct me if I am wrong.

I would really appreciate any help on the subject. This forum has already helped me in many ways, I hope to get answer to my questions soon.

Thanks in advance.

[zhangmu]

Originally Posted by mkraposhin

The library libAcoustics was developed to simulate far-field acoustics using Curle and FWH analogies with integral approach. The library was verified for monopole, dipole source and it was validated for multiple free jet flows. I would recommend you to use latest - OF1912 version. If you find bugs, please report them to issues on GitHub.

Dear mkraposhin:

I am working on the far field noise of a aerofoil FSI problem, so I coupled openfoam7 and calculix, but I noticed that the libacoustic is used on openfoam4. Is it possible that libacoustic can be used in openfoam7?

Thank you very much for your effort on this lib.

Best regards
Mu
03.01.2022

[guanjiang.chen]

Originally Posted by zhangmu

Dear mkraposhin:

I am working on the far field noise of a aerofoil FSI problem, so I coupled openfoam7 and calculix, but I noticed that the libacoustic is used on openfoam4. Is it possible that libacoustic can be used in openfoam7?

Thank you very much for your effort on this lib.

Best regards
Mu
03.01.2022

Hi,

You can try. I used the libacoustics V4 in the OpenFOAM6.

Regards,
Guanjiang

[zhangmu]

Originally Posted by guanjiang.chen

Hi,

You can try. I used the libacoustics V4 in the OpenFOAM6.

Regards,
Guanjiang

Thanks for your information, Guanjiang, I will try it first and see if it's ok.

[zhangmu]

Originally Posted by guanjiang.chen

Hi,

You can try. I used the libacoustics V4 in the OpenFOAM6.

Regards,
Guanjiang

Dear Guanjiang：

I am trying installing libacoustic in openfoam7 in Ubuntu, but after running ./wmakeAll.sh
it shows that

dell-123@Precision-7920-Tower:~/Downloads/libAcoustics-master/OpenFOAM-4.1$ ./wmakeAll.sh wmake libso . make: *** No rule to make target '/opt/openfoam7/src/OpenFOAM/lnInclude/Xfer.H', needed by 'Make/linux64GccDPInt32Opt/SoundObserver/SoundObserver.C.dep'. Stop. make: *** No rule to make target '/opt/openfoam7/src/OpenFOAM/lnInclude/Xfer.H', needed by 'Make/linux64GccDPInt32Opt/FileInterface/FileInterface.C.dep'. Stop.

After checking the directory /opt/openfoam7/src/OpenFOAM/lnInclude/, there is no file named Xfer.H, how do you solve this problem in of6?

Best regards
Mu
04.01.2022