[skeptik]

Originally Posted by Q.E.D.

Hi skeptik,



thank you for your work on this library!



The last update was a little while ago. So I just wanted to ask whether the libAcoustics library will eventually be updated to OF5.x?


Best wishes
Q.E.D.

Hi.

In any case, follow guys from ISP RAS (Moscow)

https://github.com/unicfdlab

Best wishes!

[landau]

Dear All,

First of all I would like to thank the great labour that Skeptik and his group are doing concerning to aeroacoustics.

This is my very first post in this Forum, and I am pretty informed about how to manage common errors that appeared along this thread and others... but specifically this, I can not solve it by myself.

I'm using the library libAcoustics.so during pisoFoam under OF4.1 in a very simple case that runs perfectly without using the library. What is more, I use also other libraries to, for example, calculate the force coefficients of lift/drag.

The source of this error comes from nowhere but from any misuse of this library.

The error I find is the following:

Starting time loop

forces CurleAnalogy1:
    Not including porosity effects
Curle CurleAnalogy1:
    Not including porosity effects
Reading analogy settings
Time = 0.0001

Courant Number mean: 0.004787024 max: 0.1638222
smoothSolver:  Solving for Ux, Initial residual = 0.0002232178, Final residual = 2.606655e-09, No Iterations 2
smoothSolver:  Solving for Uy, Initial residual = 0.0004308772, Final residual = 1.203743e-08, No Iterations 2
smoothSolver:  Solving for Uz, Initial residual = 0.0001465603, Final residual = 4.982442e-09, No Iterations 2
GAMG:  Solving for p, Initial residual = 0.871151, Final residual = 0.04331954, No Iterations 2
time step continuity errors : sum local = 1.586758e-08, global = -1.57957e-10, cumulative = -1.57957e-10
GAMG:  Solving for p, Initial residual = 0.04690876, Final residual = 0.001487216, No Iterations 3
time step continuity errors : sum local = 1.265232e-09, global = -8.444425e-11, cumulative = -2.424012e-10
GAMG:  Solving for p, Initial residual = 0.006935179, Final residual = 7.817335e-07, No Iterations 14
time step continuity errors : sum local = 6.804893e-13, global = -1.056938e-14, cumulative = -2.424118e-10
smoothSolver:  Solving for nuTilda, Initial residual = 0.001147876, Final residual = 1.686137e-08, No Iterations 2
ExecutionTime = 3.24 s  ClockTime = 3 s

[1]
[2]
[2]
[2] --> FOAM FATAL ERROR:
[2] [3]
[3]
[3] --> FOAM FATAL ERROR:
[3] Could not find rho
[3] [4]

And my file containing the Curle controls:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.x                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/

CurleAnalogy1
{
    functionObjectLibs ("libAcoustics.so");
    type                Curle;
    log                 true;//Logging info
    probeFrequency      1;
    patches             ("sphere");
    order               second;
    timeStart           0;
    timeEnd             0.25;
    c0                  341;//Velocity of sound in air
    dRef                4;//Domain ref for 2D computations
    pName               p; //Pressure variable name
    rhoName             rhoInf;//rho;//none
    rhoInf              1.0;
    pInf                0.0;
    CofR                (0 0 0); //origin

    observers
    {
        probeA
        {
            position    (5.0 0.0 0.0);
            pRef        0.0;
            fftFreq     1024;
        }
        probeB
        {
            position    (0.0 2.5 0.0);
            pRef        0.0;
            fftFreq     1024;
        }
    }
}


// ************************************************************************* //

I think that is something related to a redefinition of the variable rho. I tried different possibilities regarding rhoName
1) rho
2) none

and regarding rhoInf
1) 1
2) Different value

I have also tried to use/don't use the forces library unsuccessfully.


Thank you all for your time, and I am sorry if this question has got an obvious answer.

Have a nice day.

Best regards,
HBR

[xevious]

Originally Posted by skeptik

Hi.

In any case, follow guys from ISP RAS (Moscow)

https://github.com/unicfdlab

Best wishes!

Hello skeptik!


Thank you very much for the development of libAcoustics! I have a few concerns:



I am currently trying to compute the noise of a rotating propeller using fw-h. I wanted to use a faceZone i created around the propeller as the control fw-h surface, but the functionObject only accepts patches? I would like to know if the library can be updated to accept faceZones also.


Also, it would be awesome if the probeFrequency would be modified to accept actual dt independent of the simulation timestep instead of 1.


I tried to get the library to work with openfoam v1712, but i got a slew of errors during compilation errors. Are there any plans to extend the compatibility of these libraries to other versions?




Again, thanks for working on libAcoustics!

[Mecsocse]

Dear all,

Thank you very much for the development of libAcoustics! I want to use it to calculate a 3D HVAC car System.

What solver would you use for the calculation? I think a rhoPimpleFoam would be a good choice.

Are there recommendations on what is better or makes more sense to use in my case?

Thank you very much!

[Bdew8556]

Hey guys,

I was wondering if you had any thoughts on this? its the same topic.

wmake and compiling

[spalartallmaras]

Originally Posted by skeptik

It's similar like calculating forces and coefficients via libforces.so in controlDict

Is pressure calculated by linearised Euler-equations?

[alireza94]

Originally Posted by spalartallmaras

Is pressure calculated by linearised Euler-equations?

Hi

I do not think so. Using LEE to simulate the propagation of acoustic signals is much complicated and even the Ansys software does not use this method. I far as I know, this library uses integral surface methods to simulate the acoustic signals.
Integral surface methods, like Farassat or Kirchhoff method, use a data surface to simulate the signal.

I hope it would be helpful

[spalartallmaras]

Hi,

I want to use this code

https://github.com/unicfdlab/libAcoustics

but does anybody know where can I find digitef-dev-1912?

"OpenFOAM+ v.1912 is in the digitef-dev-1912 branch of the repository"

[stamufa]

@spalartallmaras just click on branch on the left and in the dropdown select the 1912 repo instead of the master

[guanjiang.chen]

Originally Posted by DAPHNE

Dear Ilya and all,

Thank you so much for sharing the information.
From the presentation material ( OFW-Seoul-Kraposhin-AcousticTrack-5 pdf) given for Curle implementation discussed in slide 9 the expression used for
acoustic pressure is p'= 1/4IIc0_ * x/r^2 *[ (df/dt) + c0 f/r].

But in the Curle .C at line 288
scalar coeff1 = 1. / 4. / Foam::constant::mathematical:: pi / c0_ / c0_ ;

forAll (observers_, iObs)
{
SoundObserver& obs = observers_[iObs];
vector l = obs.position() - c_;
scalar r = mag(l);
scalar oap = l & (dFdT + c0_ * F / r) * coeff1 / r /r;
if (dRef_ > 0.0)
{
oap /= dRef_;
}
obs.apressure(oap);
}

}
}
It is clear that oap is the expression to find the p' value. But in the expression for oap, at the denominator we have c0_^2 , which is computed from the coeff1 expression. Is there any approximation made?Could you please explain is there any approximation like nearfield or farfield behind this approximation?

Thanks in advance.

Hi Daphne,

Could you please share the OFW-Seoul-Kraposhin-AcousticTrack-5 pdf with me? I search it but don't find it.

Thanks,
Guanjiang

[guanjiang.chen]

Originally Posted by landau

Dear All,

First of all I would like to thank the great labour that Skeptik and his group are doing concerning to aeroacoustics.

This is my very first post in this Forum, and I am pretty informed about how to manage common errors that appeared along this thread and others... but specifically this, I can not solve it by myself.

I'm using the library libAcoustics.so during pisoFoam under OF4.1 in a very simple case that runs perfectly without using the library. What is more, I use also other libraries to, for example, calculate the force coefficients of lift/drag.

The source of this error comes from nowhere but from any misuse of this library.

The error I find is the following:

Starting time loop

forces CurleAnalogy1:
    Not including porosity effects
Curle CurleAnalogy1:
    Not including porosity effects
Reading analogy settings
Time = 0.0001

Courant Number mean: 0.004787024 max: 0.1638222
smoothSolver:  Solving for Ux, Initial residual = 0.0002232178, Final residual = 2.606655e-09, No Iterations 2
smoothSolver:  Solving for Uy, Initial residual = 0.0004308772, Final residual = 1.203743e-08, No Iterations 2
smoothSolver:  Solving for Uz, Initial residual = 0.0001465603, Final residual = 4.982442e-09, No Iterations 2
GAMG:  Solving for p, Initial residual = 0.871151, Final residual = 0.04331954, No Iterations 2
time step continuity errors : sum local = 1.586758e-08, global = -1.57957e-10, cumulative = -1.57957e-10
GAMG:  Solving for p, Initial residual = 0.04690876, Final residual = 0.001487216, No Iterations 3
time step continuity errors : sum local = 1.265232e-09, global = -8.444425e-11, cumulative = -2.424012e-10
GAMG:  Solving for p, Initial residual = 0.006935179, Final residual = 7.817335e-07, No Iterations 14
time step continuity errors : sum local = 6.804893e-13, global = -1.056938e-14, cumulative = -2.424118e-10
smoothSolver:  Solving for nuTilda, Initial residual = 0.001147876, Final residual = 1.686137e-08, No Iterations 2
ExecutionTime = 3.24 s  ClockTime = 3 s

[1]
[2]
[2]
[2] --> FOAM FATAL ERROR:
[2] [3]
[3]
[3] --> FOAM FATAL ERROR:
[3] Could not find rho
[3] [4]

And my file containing the Curle controls:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  4.x                                   |
|   \\  /    A nd           | Web:      www.OpenFOAM.org                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/

CurleAnalogy1
{
    functionObjectLibs ("libAcoustics.so");
    type                Curle;
    log                 true;//Logging info
    probeFrequency      1;
    patches             ("sphere");
    order               second;
    timeStart           0;
    timeEnd             0.25;
    c0                  341;//Velocity of sound in air
    dRef                4;//Domain ref for 2D computations
    pName               p; //Pressure variable name
    rhoName             rhoInf;//rho;//none
    rhoInf              1.0;
    pInf                0.0;
    CofR                (0 0 0); //origin

    observers
    {
        probeA
        {
            position    (5.0 0.0 0.0);
            pRef        0.0;
            fftFreq     1024;
        }
        probeB
        {
            position    (0.0 2.5 0.0);
            pRef        0.0;
            fftFreq     1024;
        }
    }
}


// ************************************************************************* //

I think that is something related to a redefinition of the variable rho. I tried different possibilities regarding rhoName
1) rho
2) none

and regarding rhoInf
1) 1
2) Different value

I have also tried to use/don't use the forces library unsuccessfully.


Thank you all for your time, and I am sorry if this question has got an obvious answer.

Have a nice day.

Best regards,
HBR

Hi，

This post may be helpful.
how to use acoustic lib in openfoam

Regards,
Guanjiang