Some doubts about wave generation in Basilik

[Miguel Molinos]

Dear Basilisk's users,

I am solving a case of wave-structure interaction in an off-shore wind farm, the results given by the saint-venant solver are quite impresive (Film_2_1_180.mpg) but I have three problems:

1) For some reason that I do not understand, the wave generator boundary conditions impossed in the left side are not working properly.

u.n[left]   = -radiation(H_s0*cos(2*pi*t/T_p));
h[left] = -zb[ghost] + H_s0*cos(2*pi*t/T_p);

Despite the fact H_s0 value is 1, the maximum value of eta (surface elevation) is 0.3 and the minimum is -0.3, wich have no sense (Fig h_max_45.png).

2)

3) I am trying to save my results in raster format with the idea of making some postprocess in QGIS. I know that exists the output_grd funtion, but I do not understand very well how does it works.

Can someone help me with this issues ? Thanks in advance

Cheers, Miguel

Ps : Stephane, the work of the adaptive mesh with the foundations of the wind farm it is amazing (quadtree.png).


[Miguel Molinos]

Sorry I have just two problems, the second one was a stupid question, and for some reason (also stupid) I forgot to remove it from the post.

[Stephane Popinet]

Hi Miguel,

> 1) For some reason that I do not understand, the wave generator boundary
> conditions impossed in the left side are not working properly.

It is probably working properly. This boundary condition is a relatively
crude approximation and needs to be tuned to produce the desired wave
amplitude. This is not unlike what needs to be done for a real
"wavemaker" in a wave tank (for which an empirical "transfer function"
needs to be defined).

> 3) I am trying to save my results in raster format with the idea of
> making some postprocess in QGIS. I know that exists the output_grd
> funtion, but I do not understand very well how does it works.

What is your question?

cheers,

Stephane

[Miguel Molinos]

Hi Stephane,

Thanks for your quick answer, 

It is probably working properly. This boundary condition is a relatively
crude approximation and needs to be tuned to produce the desired wave
amplitude. This is not unlike what needs to be done for a real
"wavemaker" in a wave tank (for which an empirical "transfer function"
needs to be defined).

Ok, that was a fact that I did not know. I will look for in google about  "transfer function" or just I will try to do one by my own. Maybe using my current results for diferent periods I could create a function which returns a tunned wave height for a given period.

 

What is your question?

 

My  problem comes from the point that I am not very familiariced with structure initialisation in c99( namedoptional-arguments-in-function-calls ), so I was a little confused with the sintax, but I have just understood how does it works looking at output.h and the sintax would be something like :

 

  ...
  boundary ({m, maxam});
  char name[150];
  sprintf(name,"./../RESULTADOS/eta_max_%f_%f_%f.png",
          H_s0,T_p,orientation);
  output_grd(maxam,file = name,mask = m, linear = true);
  ...

Please excuse me for this question, that was a clear example of RTFM.

cheers,

Miguel

[Chit Yan Toe]

Dear All,

I am a new user to Basilisk. May I know if the wave boundary condition ''radiation" can be used for two-phase flow simulating using Navier-Stokes solver, instead of Shallow water equations, please?

Thanks a lot,

Chit

[PYL]

Dear Toe

Radiation is a simplified  BC for Saint-Venant

Cheers

Le 23 juil. 2026 à 16:48, Chit Yan Toe <chitya...@gmail.com> a écrit :

Dear All,

--
You received this message because you are subscribed to the Google Groups "basilisk-fr" group.
To unsubscribe from this group and stop receiving emails from it, send an email to basilisk-fr...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/basilisk-fr/a9624ade-dc72-45bd-8f51-e34939779f74n%40googlegroups.com.