CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Programming & Development

Acoustic Solver with openfoam

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree59Likes

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   May 19, 2015, 02:16
Default thanks
  #41
Member
 
a_habib's Avatar
 
Ahmad Habib
Join Date: Nov 2014
Location: Aleppo, Syria
Posts: 53
Rep Power: 7
a_habib is on a distinguished road
Thanks.
Actually my problem seems to be in installing the fftw-3.3.3
the permission for righting files to /user/local ... is denied
But I'll try it again using your tips.
a_habib is offline   Reply With Quote

Old   May 19, 2015, 04:21
Default
  #42
Member
 
a_habib's Avatar
 
Ahmad Habib
Join Date: Nov 2014
Location: Aleppo, Syria
Posts: 53
Rep Power: 7
a_habib is on a distinguished road
Thanks Alot, It worked
a_habib is offline   Reply With Quote

Old   May 20, 2015, 04:02
Default
  #43
Member
 
a_habib's Avatar
 
Ahmad Habib
Join Date: Nov 2014
Location: Aleppo, Syria
Posts: 53
Rep Power: 7
a_habib is on a distinguished road
I'm Wondering if some one used this library.It's calculate the acoustic pressure and the fft to calculate the SPL sv. frequency, my question is at any point does it calculate the fft? at the end time? or during the runtime solution????
a_habib is offline   Reply With Quote

Old   May 31, 2015, 02:46
Default
  #44
Member
 
a_habib's Avatar
 
Ahmad Habib
Join Date: Nov 2014
Location: Aleppo, Syria
Posts: 53
Rep Power: 7
a_habib is on a distinguished road
Hello FOAMERS
I need a validation case to validate libAcoustic (something simple unlike the Tandem Cylinder case)
Any Help
a_habib is offline   Reply With Quote

Old   June 1, 2015, 02:39
Default
  #45
Member
 
Ilya
Join Date: Dec 2011
Location: Russia
Posts: 97
Blog Entries: 41
Rep Power: 10
skeptik is on a distinguished road
Here is a work about cavity aeroacoustic measurements, for instance

http://www.lr.tudelft.nl/fileadmin/F...ant_Parkhi.pdf
a_habib likes this.
__________________
practice makes perfect
skeptik is offline   Reply With Quote

Old   June 1, 2015, 04:35
Default
  #46
Member
 
Join Date: Jun 2012
Posts: 76
Rep Power: 9
maHein is on a distinguished road
Hello,

I was wondering why the libAcoustics does calculate an average distance between surface and observer? Why is the distance not evaluated for each face separately?

Kind regards,

Martin
maHein is offline   Reply With Quote

Old   June 1, 2015, 04:51
Default
  #47
Member
 
Ilya
Join Date: Dec 2011
Location: Russia
Posts: 97
Blog Entries: 41
Rep Power: 10
skeptik is on a distinguished road
Quote:
Originally Posted by maHein View Post
Hello,

I was wondering why the libAcoustics does calculate an average distance between surface and observer? Why is the distance not evaluated for each face separately?

Kind regards,

Martin
True. Sadly i've not developed this version of the Curle analogy, i've only adopted for 2.3 to work with it. May be we will make a revision and develop a new version.

It was found at least one error in the old realization of this library.
__________________
practice makes perfect
skeptik is offline   Reply With Quote

Old   June 1, 2015, 06:16
Default
  #48
Member
 
Join Date: Jun 2012
Posts: 76
Rep Power: 9
maHein is on a distinguished road
I am currently working on reimplementing Curle for OpenFOAM 2.4.0 to get a better understanding of acoustic analogies on the way to Ffowcs-Williams-Hawkings. That's why I came up with the question...
Alhasan likes this.
maHein is offline   Reply With Quote

Old   June 1, 2015, 07:07
Default
  #49
Member
 
Ilya
Join Date: Dec 2011
Location: Russia
Posts: 97
Blog Entries: 41
Rep Power: 10
skeptik is on a distinguished road
Quote:
Originally Posted by maHein View Post
I am currently working on reimplementing Curle for OpenFOAM 2.4.0 to get a better understanding of acoustic analogies on the way to Ffowcs-Williams-Hawkings. That's why I came up with the question...
It's nice question and nice challenge. We're developing FWH in addition to Curle now and if you find some errors in libAcoustics, please, report. I hope we will have a time to review old versions and to make a test-cases and validate our results more.
Alhasan likes this.
__________________
practice makes perfect
skeptik is offline   Reply With Quote

Old   June 2, 2015, 02:40
Default
  #50
Member
 
a_habib's Avatar
 
Ahmad Habib
Join Date: Nov 2014
Location: Aleppo, Syria
Posts: 53
Rep Power: 7
a_habib is on a distinguished road
What is the ((dRef)) in the lib code??
Is it the the long in the z direction if the simulation is 2D [x,y]
If so, what I should use for it in the 3D simulations

thanks in advance
a_habib is offline   Reply With Quote

Old   June 2, 2015, 14:29
Default
  #51
Member
 
Join Date: Jun 2012
Posts: 76
Rep Power: 9
maHein is on a distinguished road
If you set dRef to zero, it is not considered in the calculations. If you set the value, the pressure fluctuations are divided by dRef.

I think this is only used for 2D simulations.
skeptik and a_habib like this.
maHein is offline   Reply With Quote

Old   June 4, 2015, 02:45
Default
  #52
Member
 
Ilya
Join Date: Dec 2011
Location: Russia
Posts: 97
Blog Entries: 41
Rep Power: 10
skeptik is on a distinguished road
Quote:
Originally Posted by a_habib View Post
What is the ((dRef)) in the lib code??
Is it the the long in the z direction if the simulation is 2D [x,y]
If so, what I should use for it in the 3D simulations

thanks in advance
If you solve 2D problem dRef is your mesh dZ.
If you solve 3D problem assign to dRef any negative value.
a_habib and Poompil like this.
__________________
practice makes perfect
skeptik is offline   Reply With Quote

Old   June 21, 2015, 16:11
Exclamation
  #53
Member
 
a_habib's Avatar
 
Ahmad Habib
Join Date: Nov 2014
Location: Aleppo, Syria
Posts: 53
Rep Power: 7
a_habib is on a distinguished road
Hello.
I tried to validate this analogy using the paper ((Two and Three-Dimensional Simulation of Sound Generated by Flow Around a Circular Cylinder - 30th AIAA Aeroacoustics Conference)).
every thing was good as you can see my results except when I calculated the SPL & OASPL for different cylinder span length. The result where on the opposite, the higher SPL in my calculation where related to the shortest cylinder (in the paper where related to the longest cylinder).
any one can tell me why this happened.
you can check my controlDit


SPL.jpg

controlDict.txt

Results1.jpg

Results2.jpg
skeptik likes this.
a_habib is offline   Reply With Quote

Old   July 20, 2015, 10:15
Default
  #54
Member
 
Join Date: Jun 2012
Posts: 76
Rep Power: 9
maHein is on a distinguished road
I simulated the NASA tandem cylinder validation case using a Spalart Allmaras DDES turbulence model with a span length of 3 times the diameter. The results are quite satisfactory and similar to other publications on this case.

maHein is offline   Reply With Quote

Old   July 21, 2015, 04:29
Default
  #55
Member
 
Ilya
Join Date: Dec 2011
Location: Russia
Posts: 97
Blog Entries: 41
Rep Power: 10
skeptik is on a distinguished road
Quote:
Originally Posted by maHein View Post
I simulated the NASA tandem cylinder validation case using a Spalart Allmaras DDES turbulence model with a span length of 3 times the diameter. The results are quite satisfactory and similar to other publications on this case.

Very nice results.

I have few questions to clarify DDES-related problems:
1. Did you measure y+? How much is it?
2. What's about wallFunctions? Did you use it? (connected to 1. question)
3. Can you show your fvSchemes file? Or at least say what was your grad and div schemes?

Thank you in advance.
__________________
practice makes perfect
skeptik is offline   Reply With Quote

Old   July 21, 2015, 06:27
Default
  #56
Member
 
Join Date: Jun 2012
Posts: 76
Rep Power: 9
maHein is on a distinguished road
Hello,

the mesh contains contains 8 mio cells with an average y+ value of about 1.9 for the first and 1.4 for the second cylinder. I also prepared two finer meshes but did not test them yet. For nuSgs I used the nutLowReWallFunction and fixedValue 0.0 for nuTilda.

My fvSchemes looks as following:

Code:
ddtSchemes
{
    default         backward;
}

gradSchemes
{
    default         Gauss linear;
}

divSchemes
{
    default          Gauss linear;
}

laplacianSchemes
{
    div(phi,U)       Gauss LUST grad(U);
    div(phi,nuTilda) Gauss linearUpwind grad(nuTilda);

    div((nuEff*dev(T(grad(U))))) Gauss linear;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default         corrected;
}

fluxRequired
{
    default         no;
    p;
}
I tried Gauss linear for div(phi,U), but it caused massive checkerboarding. Maybe a less diffusive scheme for div(phi,nuTilda) could also be tested.

Regards,

Martin
maHein is offline   Reply With Quote

Old   July 21, 2015, 10:35
Default
  #57
Member
 
Ilya
Join Date: Dec 2011
Location: Russia
Posts: 97
Blog Entries: 41
Rep Power: 10
skeptik is on a distinguished road
Quote:
Originally Posted by maHein View Post
Hello,

the mesh contains contains 8 mio cells with an average y+ value of about 1.9 for the first and 1.4 for the second cylinder. I also prepared two finer meshes but did not test them yet. For nuSgs I used the nutLowReWallFunction and fixedValue 0.0 for nuTilda.

My fvSchemes looks as following:

Code:
ddtSchemes
{
    default         backward;
}

gradSchemes
{
    default         Gauss linear;
}

divSchemes
{
    default          Gauss linear;
}

laplacianSchemes
{
    div(phi,U)       Gauss LUST grad(U);
    div(phi,nuTilda) Gauss linearUpwind grad(nuTilda);

    div((nuEff*dev(T(grad(U))))) Gauss linear;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
    default         corrected;
}

fluxRequired
{
    default         no;
    p;
}
I tried Gauss linear for div(phi,U), but it caused massive checkerboarding. Maybe a less diffusive scheme for div(phi,nuTilda) could also be tested.

Regards,

Martin
Why laplacian

Code:
laplacianSchemes
{
    div(phi,U)       Gauss LUST grad(U);
    div(phi,nuTilda) Gauss linearUpwind grad(nuTilda);

    div((nuEff*dev(T(grad(U))))) Gauss linear;
}
?

May be

Code:
divSchemes
{
    div(phi,U)       Gauss LUST grad(U);
    div(phi,nuTilda) Gauss linearUpwind grad(nuTilda);

    div((nuEff*dev(T(grad(U))))) Gauss linear;
}
?
__________________
practice makes perfect
skeptik is offline   Reply With Quote

Old   July 21, 2015, 11:02
Default
  #58
Member
 
Join Date: Jun 2012
Posts: 76
Rep Power: 9
maHein is on a distinguished road
ups, that's my mistake! I mixed up the settings... Now I have to rerun everything ...
maHein is offline   Reply With Quote

Old   July 22, 2015, 02:13
Default
  #59
Member
 
Ilya
Join Date: Dec 2011
Location: Russia
Posts: 97
Blog Entries: 41
Rep Power: 10
skeptik is on a distinguished road
Quote:
Originally Posted by maHein View Post
ups, that's my mistake! I mixed up the settings... Now I have to rerun everything ...
Wow.
We spent a huge time and resources investigating different numerical schemes, may be we should try something like yours. Despite such errors you get good results, something in your fvSchemes was ignored but something not) will see.
Which version you use?
__________________
practice makes perfect
skeptik is offline   Reply With Quote

Old   July 27, 2015, 08:12
Default
  #60
Member
 
Join Date: Jun 2012
Posts: 76
Rep Power: 9
maHein is on a distinguished road
I'm using OpenFOAM 2.4.0.

I'm currently rerunning the simulation with the correct settings. I can show you the results in a few days.

Regards,

Martin
maHein is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Working directory via command line Luiz CFX 4 March 6, 2011 20:02
Running Problem using Openfoam solver cfd_staruser OpenFOAM 5 August 14, 2009 02:28
64bitrhel5 OF installation instructions mirko OpenFOAM Installation 2 August 12, 2008 18:07
why the solver reject it? Anyone with experience? bearcat CFX 6 April 28, 2008 14:08
OpenFOAM Training and Workshop Zagreb 2628Jan2006 hjasak OpenFOAM 1 February 2, 2006 21:07


All times are GMT -4. The time now is 07:48.