CFD Online Discussion Forums - waves2Foam waveFlume reflections

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waves2Foam waveFlume reflections

Hello - I have just installed the waves2Foam library on OFv2.1.1 and have run the tutorial waveFlume. The wave appears linear at the beginning but soon there is a reflected wave that distorts the incoming wave. The video is here: http://youtu.be/VwNF65Fkdbo
Can anyone offer an explanation or a fix??
Thank you,
Betsy

Ok, I have extended the domain length and it appears the left running wave interfering with the right running wave is not a reflection. Here is a video: http://youtu.be/yfZ1eXDDa4s
Again, I'm not sure what is causing this. Any help is appreciated.
Thanks,
Betsy

Betsy,
Your wave's amplitude appear to be quite large relative to the wave length which may mean that linear wave theory might not be the best choice. Try running smaller wave amplitudes and see if the behavior persist. I have not had any issues with strange behavior in that tutorial for reasonable amplitudes.

Dave

Hi Betsy

What you see is exactly caused by the large amplitude linear wave in shallow waters. The explanation is as follows:

Quote:

The first example is the spatial change of a sinusoidal wave of finite wave height, which is generated at the inlet over a horizontal bed. The prescribed sinusoidal motion does not satisfy the complete non-linear wave problem, hence bound higher order harmonics are generated adjacent to the boundary. In order to fulfil the first order theory at the boundary, however, spurious free higher harmonics are likewise created, which have amplitudes equal to their bound counterparts, but with opposite phase, such that they cancel one another at the inlet. Interaction between these harmonics leads to an energy transfer, which can be identified as beat lengths, see [24] for further details.

where the quote is taken from our article:
@article { jacobsenFuhrmanFredsoe2011,
Author = {Jacobsen, N G and Fuhrman, D R and Freds\o{}e, J},
title = {{ A Wave Generation Toolbox for the Open-Source CFD Library: OpenFoam\textregistered{} } },
Journal = {{ Int. J. Numerl. Meth. Fluids} },
Year = {In print},
Volume = {},
Pages = {},
DOI = {{10.1002/fld.2726} },
}

If you choose stokesSecond instead, you should experience that the rate of energy exchange decreases, since the spurious waves generated will be of third order.

Kind regards,

Niels

Yes, this makes sense. Thank you both for your replies.
Betsy

An error in waveFlume test of waves2Foam

Hy guys,
I tried to run the tutorial waveFlume from waves2Foam. I run blockMesh and the mesh generated successfully. Now I want to see the mesh by paraview and after typing: paraFoam I got this error :

WARN file does not exist:
./system/fvSchemes
./system/fvSolution
created temporary 'waveFlume.OpenFOAM'
Application asked to unregister timer 0x63000017 which is not registered in this thread. Fix application.

My OpenFOAM version is 2.1.1. Would you tell me how can I fix this error?

Thanks

Hi guys,
Is there a user guide for using waves2Foam?

Hi,

The only thing around would be the forum and especially this thread:

http://www.cfd-online.com/Forums/ope...ed-topics.html

and the wiki-page

http://openfoamwiki.net/index.php/Contrib/waves2Foam

Kind regards

Niels