[kmargaris]

Hi Pablo,

What is the purpose of nEdgeMin and nEdgeMax settings. According to the Wiki page they are used in 2D and 3D wave absorption and:

"nEdgeMin and nEdgeMax solve some issues that appear on the corners, selecting a number of paddles that are only capable of taking water out according to the 2D theory"

What sort of problems do they address?

Best regards,
Kostas

[Phicau]

Hi Kostas,

check the user guide included in the reference materials.

- It solves a situation in which pumping water in very narrow spaces (i.e. acute corner) would make the free surface reach the atmosphere and decrease dt.
- It solves a situation with the 3D absorption code, which measures tangential velocity and uses that as a factor to calculate the incident angle, since the absorption velocity of an edge will be the tangential velocity of the neighbouring boundary.

Dear all,

I detected a bug yesterday evening and decided to postpone the release of the flap wavemaker until that was fixed. It is fixed now and I have uploaded the code into GitHub.

This time I have only produced tutorials for the latest version of OpenFOAM (3-4*) and foam-Extend (3.2).

Unfortunately the version for foam-Extend does not have the proper BCs in some cases (see http://www.cfd-online.com/Forums/ope...ctorfield.html ) and it only runs in serial due to a weird bug, which I think it is not in olaFoam code. I will keep trying to correct that.

Best,

Pablo

[ashkan]

Hi Pablo,

First of all, thank you very much for your interesting olaFoam solver. I have been using it for generating various wave types and was just looking to use the Streamfunction wave theory. I looked into "FourierFenton" directory to generate the coefficients but could not run the Fourier.exe code (I am using Ubuntu 16.04). I also downloaded the package from John Fenton's page but could not compile the code (it seems that process.h file is missing).

I was wondering if you have any working version or any comments on how to generate the coefficients.

Regards
Ashkan

[Phicau]

Hi Ashkan,

you need to run the version provided, because the newer ones provide results in a different way, which is not suitable for what olaFoam accepts.

There is no problem running Fourier.exe in linux, as long as you get wine:

sudo add-apt-repository ppa:wine/wine-builds
sudo apt-get update
sudo apt-get install winehq-devel

wine Fourier.exe

(first time you will need to install some dependencies, just click yes in all the prompts)

Best,

Pablo

[ashkan]

Originally Posted by Phicau

Hi Ashkan,

you need to run the version provided, because the newer ones provide results in a different way, which is not suitable for what olaFoam accepts.

There is no problem running Fourier.exe in linux, as long as you get wine:

sudo add-apt-repository ppa:wine/wine-builds
sudo apt-get update
sudo apt-get install winehq-devel

wine Fourier.exe

(first time you will need to install some dependencies, just click yes in all the prompts)

Best,

Pablo

Many thanks Pablo. I installed wine as you suggested and all is working fine now.

Many thanks again
Ashkan

[kasra karimi]

Dear all:

I am using OlaFoam to generating waves in a 3-D flume (12*2.2*1m) and my turbulent model is k-omega SST.

i have experienced a problem through running number of cases for different waves, I don't know if I have done something wrong or its a bug or something. i have tried it for different size of mesh but no progress.I have stuck with this problem for a month, please help me

the model works perfectly in 2D model, but the problem is that when it comes to 3D model, after 5-6 wave period "k" would increase suddenly from quantities near 0 to 3000.This would lead to decreasing the time steps to very low and the simulation wont progress more!

In my latest try it happened for some of the cells at the outlet boundary. I have put some snapshots of "alpha" and "k" together in the below picture + the mesh I used:





*here is what I applied to the outlet B.C:
for "k"

internalField   uniform 1.35e-5;

boundaryField
{

    outlet
    {
        type            zeroGradient;

    }

for "U"

internalField   uniform (0 0 0);
outlet
    {
        type            waveAbsorption2DVelocity;
        value           uniform (0 0 0);
    }

for "Omega"

internalField   uniform 136;

boundaryField
{
    outlet
    {
        type            zeroGradient;
    }

[Phicau]

Hi Kasra,

I think you might be experiencing that because of a pressure instability, please check whether you obtain abnormal pressures/velocities at that location.

I notice that you mesh is made from triangular prisms, and that the smearing of the VOF function is very significant (probably this is the root of the problem, as VOF should be as sharp as possible). From my practical knowledge, I will advice you against using triangles in the mesh to avoid such problems. Try with a structured mesh.

Best,

Pablo

[kasra karimi]

Originally Posted by Phicau

Hi Kasra,

I think you might be experiencing that because of a pressure instability, please check whether you obtain abnormal pressures/velocities at that location.

I notice that you mesh is made from triangular prisms, and that the smearing of the VOF function is very significant (probably this is the root of the problem, as VOF should be as sharp as possible). From my practical knowledge, I will advice you against using triangles in the mesh to avoid such problems. Try with a structured mesh.

Best,

Pablo

Hi Pablo,

Thanks a lot for your reply, well as you said there are also abnormal pressure near this location, but the velocity seems ok

p_rgh

     outlet 
    {
        type            fixedFluxPressure;
        value           uniform 0;
    }

and about the mesh, it may seems strange but my wanted result (which is the time-averaged flow pattern) is only correct by using triangular mesh! at first for my 2D model I generated structured mesh with different sizes and via different methods(blockMesh, snappy, SALOME, Gambit), but all of them failed to simulate the correct pattern, but when I used triangular mesh with the same B.C and ..., the result were perfect.

so besides changing the mesh, do you think of any other way that could stabilize the model? would changing the turbulent model to k-Epsilon be helpful?

Best
Kasra

[Phicau]

Hi Kasra,

pressure and velocity are coupled, large pressure gradients will induce crazy velocities.

Maybe some things can help there:

- Having smaller cells in a wider vertical region
- Increasing the value of cAlpha to avoid smearing of the free surface

Best,

Pablo

[smh]

Dear Pablo,
Hello

In the waveDict file we introduce the waveTheory and waveType.
I wanted to know if it's possible to use waveTheory.py to include the waveTheory and waveType automatically with the given h,T & H for the desired problem without any change in waveDict file?

Best regards,

Mahdi

[HosseinB]

Hi Pablo,

I am preparing a document and need to cite olaFoam. How can I cite this?

I am also acknowledging your help with my work in the document. I want to know if that's OK with you.

Cheers,
Hossein

[Phicau]

Dear Mahdi,

at this stage the waveTheory.py script only represents the selected wave conditions. I have not plans to make it generate a waveDict file, as there are lots of other options in the waveDict file that do not intervene in selecting the wave theory.

Dear Hossein,

that is great news, congratulations! Thanks for acknowledging my help.

Since I am still preparing a couple papers to formally introduce olaFoam, please find in this link some information/references on how to cite olafoam at this stage:

https://openfoamwiki.net/index.php/C...ces_and_Citing

Do let me know when the paper is published and I will update the list to include it for other users to know.

Best regards,

Pablo

[smh]

Dear Pablo,
Hello

Thanks for your reply.
Another question.
Totally is it possible to apply the wave absorption BC on oblique faces?
Actually I did this but the outlet face act as wave generation BC.
I look forward to have your valuable comments.

Best regards,

Mahdi

[abas.rahmani86]

Dear Pablo
hello
thank you for olaFoam and your reply
I have a question
I have a problem with insert shapes in domain.
how i can to change direction of wave in waveDict?
Best regards

[fusij]

Hi,

I need to simulate a coastal process (e.g. wastewater discharge) where there is need to run the simulation for several hours of simulated time. During this time span there will be considerable change in the tide level. The domain range will be ~10 km. The goal here is simulate a scalar transport in a vector field on a rather large scale. Is it possible with OLAFOAM to create surface waves at the inlet boundary along with changing the tide level at the same time (waves with much lower frequency). That is applying two waves of different frequencies at the same time for the alpha field at the inlet. The change in water level representing the tides, only involves change in alpha not in velocity.

Summary of what I want:
Surface waves (e.g. StokesI, relatively high frequency) affecting alpha and U field
+
Tidal waves only affecting alpha (low frequency)

[Phicau]

Hi fusij,

olaFoam can do that. However, you are not going to be able to simulate your conditions with OpenFOAM due to computational cost issues: your domain is too large and the simulation time will be too long for this 3D RANS model.

Best,

Pablo

[fusij]

Thanks for the answer. It really depends on what you are trying to resolve. It all comes down to your cell sizes. This problem is usually solved with rather large cells when investigating the farfield conditions. So you come down to mesh sizes of several mill. cells. Commercial software even solve this problem on a few hundred thousand cells, lowering vertical resolution. Such large cells and timestep are maybe problematic for the surface waves but the tide wave can be resolved accurately.

Sent from my SM-G920F using CFD Online Forum mobile app

[abas.rahmani86]

hi pablo
I have a problem with simulating wave with period less than 3 sec by olafoam
I try to simulate a flume without any structure and get a regular wave in it
but after 30 second i see irregularity in wave.the photo show wave gage at 3,8 and 12 meter from begining of flume(wave maker).I attach source file too.
wave period=1.67 sec
wave height=0.175 m
water depth=0.8 m
I really confuse because i change every parameter for it.
do you meet this ever?
many thanks for your reply Pablo.
abas rahmani
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[totalBeginner]

Hey Pablo!

I've been working with OlaFOAM for a while now and am starting something new. I want to simulate particles in the fluid, that are supposed to be moved my the waves. But to combine olaFoam and a solidParticle-solver, I need to use an RAS turbulence model.

Now my question: Does that even work with olaFoam?

Cheers, Kryss

[Phicau]

Hi Abas,

I will take a look at that and report back to you.

Hi Kryss,

Yes, olaFoam can work with RAS and virtually any turbulence model that works with OpenFOAM. Regarding the particles, I did some work years ago. It works, but when moving to 3D scaling is a DISASTER due to the huge number of particles.

Best,

Pablo