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Hi Forum!

I have been struggling for a long time with an artemis model over a strech of coast in the Baltic Sea. At this point it feels like I've tried it all - from bathymetry smoothings to mesh resolution, boundary conditions and different setups. I keep getting unrealistic wave patterns.

Do any of you out there recognize the problem, and know how to cope with it?

Attached is a picture of wave height with the 1m bottom contours added.


Best wishes, schmirre

Hi Schmirre,

Sorry for the late reply. Have you managed to solve your issue?

It appears that your 'offshore' boundary is not 'offshore' enough and that shoaling occurs right after or at the boundary. There are two options:

1. Move the offshore boundary deeper
2. Create an offshore model with TOMAWAC and chain it to ARTEMIS

If this is still open, we can discuss the particulars.

Best Regards,
Costas

Hi Costas,

Thanks for replying. I managed to get acceptable results by moving the offshore boundary deeper, and also by smoothing the bathymetry at the boundary (with pre-processing tools) to make it more uniform.

I have used TOMAWAC-spectrums as input for ARTEMIS earlier, and that works fine! This time I had access to good wave data, and therefore felt that it was better to use that directly.

From your experience, do you haveany general advice for "how far offshore" the boundary should be? Sometimes deep water conditions, and even transitional, are very far from shore, and thus the computational cost will be too large?

Best wishes, Schmirre

Hi Schmirre,

Since TOMAWAC-ARTEMIS chaining was implemented, I haven't used ARTEMIS standalone really. Since TOMAWAC pre-refracts the wave and modifies the spectrum, you can set the boundary right up to the coast. Therefore you can fit the ARTEMIS grid to the area needed most, reducing computation time. In addition, according to the manual, solving ARTEMIS equation is more computationally intensive in deeper waters and the other way round for TOMAWAC.

For most cases, you generate boundary conditions with TOMAWAC once and run many ARTEMIS layout configurations.

Best Regards,
Costas

Hi again Costas,

So in my specific case, where I have a pre-defined extreme event I want to simulate (lets say a combined 100-year event with a pre-defined storm surge and a wave height), you simply run the TOMAWAC-model giving the preferred output (at least waves). That would somehow end up in a pretty iterative process, right?

Even though this might be a little off topic, I have another question. Have you ever used ECMWF wind fields as input for TOMAWAC?

Best wishes, Schmirre

TOMAWAC can impose wave spectrum at the boundary nodes of ARTEMIS. Water level should be addressed in the steering file. You can read more about it in this topic: Tomawac - Artemis chaining

My domains are relatively small and so far I have only used spatially constant winds (some sourced from ERA5 dataset, not ECMWF IFS). If you want to use spatially varying wind fileds, there is a Telemac2D example called 'wind_txy' that you can get inspiration from.
Costas