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Hello everyone,

I'm trying to modelize waves breaking over a reef and flooding an island (like an atoll) with both dry zones and wet zones.

In a first approach I set the ocean boundary condition as a liquid boundary with prescribed H, where H represent the incident wave height, and let the boundary of the lagoon as a free liquid boundary. The propagation seems to be ok except for the velocities on the dry zones (too high). I have tried different parameters but the flow velocity is still too important and leads water to overflow solid structures that should normally stay dry.

My guess is that I have too much water going through the reef because of my way of simulating the incident waves. Is there a more appropriate method ?

In a second approach, I used tomawac to generate wind-induced waves arriving on my study area. How can I use the results from tomawac to simulate the flooding caused by the breaking waves ?

Thanks a lot for your help,
Regards,

Loïc

Hello,

What we probably lack here in Telemac-2D is a model representing breaking waves, I suppose you tried a higher friction, did you try head losses ?

The incident waves are better simulated with Thompson's boundary conditions.

Tomawac can provide the forcing terms due to the breaking waves, in this case you do not provide the waves as boundary condition, it is just an averaged forcing term in the momentum. When Tomawac is used like this, the overtopping is computed by empirical formulas.

With best regards,

Jean-Michel Hervouet

Hello Jean-Michel,

Indeed i tried high friction and a high velocity diffusivity but the flow velocity remains too important. I haven't tried head losses yet.
Do I need to modify the source.f subroutine to do so ?

I do use Thompson's boundary conditions for the liquid boundaries.

I'm not sure if I understood the second part.
If I want to use Tomawac results, I just have to do the coupling with Telemac 2D and remove the boundary representing the breaking wave area ?

Thanks a lot for your help,

Best regards,

Loïc

Hello,

Yes, for head losses, you need to implement source.f, see my recent posts to pilou123 for more details and to understand what does S1U.

>If I want to use Tomawac results, I just have to do the coupling with Telemac >2D and remove the boundary representing the breaking wave area ?

I am not sure to understand what is in your model and what is not, as you mention also dry zones in the model. Basically for waves overtopping a dyke, the domain stops before the dyke and empirical formulas based on the level given by Telemac and the significant wave height given by Tomawac give the quantity of water that goes over the dyke. A more phenomenological approach (your approach it seems) would consist in really adding the waves as a boundary conditions of Telemac-3D, including the dyke in the model, to model the run up, then the breaking zone would not be a boundary but a zone where we add head losses.

Regards,

JMH