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[waves2Foam] NWT wave generation problem

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Old   April 24, 2016, 05:54
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song sung jin
Join Date: Dec 2014
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Hi Niels,

I am a openFOAM beginner and I am sorry but my English is not very good.

first of all, thank you for such a good wave generation and absorption toolbox and I really appreciate your continuous effort in helping everyone out through this forum.

I have been using waves2foam for about a couple of months now and my ultimate research goal is to use it for fluid structure interaction, particularly to study wave run up and air gap through semi-submersible structure.

Above all, I have to validate wave propagation about incident wave (M1, M2) in the paper "Comparative study on airgap under floating
platforms and run-up along platform columns" by Finn Gunnar Nielsen (Fig. 1)


since I am interested in simulations based on 2D full scale flumes I started with the waveFlume tutorial and was doing some sensitivity analysis with a bunch of different parameters for a comparison with theoretical ( domain size, inlet/outlet lengths of relaxation zone, grid density, cell aspect ratio, time step per on wave length, wave steepness, etc) based on this forum and various thesis and research papers. However, my problem is a phenomenon where there is phase shift as the waves propagate through the domain right after inlet relaxation zone(Fig.2 in attachment). Fig.2-2 is only test section of Fig.2 in waveflume.

in detail, I have tried like that grid number 50~400 in one wavelength and 4~60 in one wave height in grid density, AR=1, 1.2, 1.5, 5, 7, 9 (aspect ratio), time steps 1000~9000 in on wave period and model scale, etc.

I checked the effect of wave steepness (H/L) in the steepness 0.0041 ( height 0.01m, period 1.25s, wavelength 2.4375m. but there was no wave phase shift phenomenon (Fig. 3). Fig.3-2 is only test section of Fig.3 in waveflume. and changed relaxationFactors U = 0.99 in fvsolution, it showed a good agreement (Fig. 4). Fig.4-2 is only test section of Fig.4 in waveflume. but this value was only effective on wave condition (M1). I think relaxationFactors value is meaningless in my problem.

I really want to solve this problem..

The sample case files are attached (I'm using waveFoam with OF 2.4.0).

https://drive.google.com/open?id=0B-...Xlja1JTYlMtZkk

Any answers or explanations are appreciated. Thanks!

regards,

Song

Fig.1.jpg

Fig.2.jpg

Fig.3.jpg

Fig.3-2.jpg

Fig4.jpg

Last edited by wyldckat; August 25, 2018 at 10:01. Reason: merged posts a few minutes apart
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