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Hello,

I want to simulate transmissive structures with ARTEMIS. I know that out of the box, ARTEMIS is unable to take transmission into account. However, I came across the following reports from a project carried out at HR Wallingford, that claim to have develop a method to address this problem.

Is it possible to have these reports? I am unable to find a source online.
The reports are:andThank you in advance.

Best Regards,
Costas

Hello,

(I was just looking at your posts on the use SOLVER 9 with ARTEMIS -- I will try it on our local HPC -- did you managed to make it work in the end ?)

So to answer your question: Guilty as charged.

Indeed we have done work on simulation of transmissive structures with ARTEMIS. The report you are refering to dates from 2009 (version v5p5!). I will describe the principles of the method in my next post (together with some graphics) but please note that:

- the method and calculation parts are still commerically sensitive, so you will have to fill in the blanks and work out the calculations (no problem if you publish the complete method at the next TELEMAC conference if you find it)

- we are nowadays using another method, which you might consider, whereby we do one run without the breakwater and one with the breakwater, the combination of both you can prorate according to your reflextion coefficients (with the breakwater) and transmission through.

... to be continued.

Sébastien.

(continued) ...

So, the story is that we looked at 5 previous research and consultancy projects (carried out at/by HR Wallingford) which investigated wave transmission in a flume. These studies included transmission generated solely by wave overtopping and transmission through permeable layers. The structures comprised of a mixture of caisson breakwaters, rubble mound breakwaters and concrete armoured mound breakwaters. These studies included measured spectral data for a number of physical modelling experiments.

The measured data were then been compared with prediction methods including: Goda and Kakizaki (1966) with the modification from Takahashi (Tsinker 2004) for caisson transmission and Van der Meer et al (2004) and Briganti et al (2004) for transmission over rubble mound structures.

On the ARTEMIS side, we eventually choose to implement those transmissive structure as a discontinuous wall (a row of rectangular islands/blocks with gaps in between). By varying the relative size of the blocks and gaps, the transmission coefficient can be varied. Changing the reflection coefficient of the blocks simulates absorption of wave energy. We also worked out what ration of the wavelength the block unit size and width should be.
The main issue, however, remains that the block size is determined based on the wavelength, which means that you need to change your mesh for every wavelength tested.
One of the control test was an open gap. The resultant wave height field is shown below. The wave pattern is consistent with the diffraction pattern caused by waves propagating through a gap shown in Oceanographical Engineering (Skalak 1964). The effect of the structure including the reflexion is clearly visible.

Enjoy !

Sébastien.

Hello Sebastien,

Thank you for the information you could provide. It is an interesting approach but quite labor intensive. The alternative approach is simpler, but probably not as 'exact'. Certainly more attractive.

I am investigating the sediment transport behind a detached breakwater and the only practical way of modeling transmission so far, is varying the crest depth. The breakwater is generally meant to be low crested. The main aim of the study is sediment bypass around a small harbor and the breakwater is of secondary importance, so I am prepared to make some compromises. Have you assessed the performance of Artemis in modeling submerged breakwaters?

Regarding your question about SOLVER 9 option, I will elaborate in the related post.

Best Regards,
Costas

Hello,

Five years later, I am also interested by your discussion about simulating energy transmission through harbour structures in ARTEMIS.

Is there any update/upgrade in 2020 (nearly 2021) ?

This feature is dreadfully missing...

Thank you in advance!
JBS.