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TOPIC: Creating Curved Boundaries

Creating Curved Boundaries 5 years 10 months ago #32467

  • buckle
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Is there a provision in Blue kenune to make a curved Boundary instead of a open boundary.
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Creating Curved Boundaries 5 years 10 months ago #32483

  • Karki
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What do you mean by curved boundary? Do you mean the shape of your boundary should be curved? If it is so, then it is not the bluekenue problem. It depends on the shape of your domain or study area.

If you mean the type of boundary, then you can change it according to your requirement, like open boundary with prescribed Q, the open boundary with prescribed H, etc. You can do it while making the boundary condition file in blue kenue.

Hope it helps.

Regards,
saroj
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Creating Curved Boundaries 5 years 10 months ago #32602

  • buckle
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Dear Sir,
My query is not on the type of boundary condition, but the shape of the offshore boundary. Instead of a straight offshore boundary i want to make a curved offshore boundary since my coastline is complicated.
In blue kenue there is an option for drawing only straight lines. I tried resampling but it gave sharp edges on the curve.
Later on, I tried making a curve in another drawing tool and imported in blue kenue and I am successful it.
Thank you
With regards,
Buckle S
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Creating Curved Boundaries 5 years 10 months ago #32605

  • Karki
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Yes.
Basically I also create the shape in ArcGIS and import it in Blue kenue to create the mesh of my domain.

Regards
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Creating Curved Boundaries 5 years 10 months ago #32606

  • buckle
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Dear Sir,
Another query.
Mesh generation in Blue Kenue follows edge growth ratio that means mesh size increases gradually from the boundary.
I need finer meshes in some regions of my domain.
For example in mike we can separate the domain into polygons and prescribe the size of the mesh to be generated.
Is there any method in Blue kenue through which finer meshes can be generated?
I tried reducing the edge growth ratio. But it takes days to generate but the quality of meshes doesn't seem to be good.
Is segregating the domain and generating meshes a good option?
Can you help me out in this topic?
Thank you,
With Regards
Buckle S
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Creating Curved Boundaries 5 years 10 months ago #32608

  • c.coulet
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Hi
In BK you could also define density area. This is perfectly describe in the user manual
Edge growth ratio is just a parameter to control the mesh length increase from between triangles if you give constraint size localy (with hardlines or density area)

Regards
Christophe
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Creating Curved Boundaries 5 years 10 months ago #32609

  • Karki
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In the T3 Mesh, there are different headings like
1) outline (your main boundary of the mesh)
2) Density
3)Hard Points
4)Hardlines
.......
.......

If you want finer mesh around some areas inside your main boundary, then you need to make the shape (new closed line inside blue Kenue) of that area and give a value which is your required fine mesh size inside that area. (See fig 1, attached- Here I give 0.01m for that area).

After you make the area and give the value, drag that area (newclosedLine in this case) to density heading under T3 Mesh.

Now in the T3Mesh properties, give the length of the mesh required in the other areas except that finer area (Here I give 0.02m). And then run as usual.

Now you can see (as in the attached images) that the mesh size is finer (0.01m) inside the density area whereas in other areas it is 0.02m.

You can find these steps in the manual of Blue Kenue also.

Hope this helps.

Regards,
Saroj
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Creating Curved Boundaries 5 years 10 months ago #32621

  • a.barton
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Could someone please help me understand the issue being raised?

For me, curves in some software are created via "Bézier curves" and have control points so that the shape can be managed/controlled. Is this what people are using other software to do?

Also, for me, when I zoom in on a coast (at a given resolution) the coast becomes a set of lines. And when I zoom out again, I end up with "curves".

By analogy, the former is like a "vector" image while the latter is like a "raster" image; because one can keep zooming and zooming and still have a curve in the first case while one ends up with lines in the second case after some zooming...

I am interested in hearing more about curves... for example, why do people need such an accurate representation of a coast? And why aren't lines "good enough"... is it a matter of time to create the coastal outline by the modeller because the domain is large and the coast needs to be more quickly created or is that the simulations are not accurate enough in a local region?

Kindly,
Alan
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Creating Curved Boundaries 5 years 10 months ago #32644

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Dear Alan
Not sure to fully answer your question or the problem but as far as I understand, the main goal was to create a marine limit which could be curved...
This is to avoid sharp angle in some area where the flow are more linked to tide and in which we could encountered problem on angles.
As it was written, usually this could be managed by managing the boundary creation in a GIS software and imported in BK
Nevertheless i think this will now directly possible with the simple geometry capabilities of BK
Then I'm not sure this is a real problem now...
Kind regards
Christophe
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