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Hi,

I checked your meshes and Mesh_02 seems to have this issue at the offshore boundaries. If you keep the 'resample outline' unchecked, then you need to resample the offshore boundary manually. Give the boundary a node spacing that is similar to the element sizes that you require.

I personally never do manual resampling and let blue kenue do it for me, but I always add some extra nodes along the length of the offshore outline.

However, I have noticed that in order for it to work properly, you need a density mesh that extends outside of the offshore outline. In your case I would create a new outline that extends say 5000 metres (if I understood the scale correctly) outside your offshore boundaries (not land boundary) and use it to create a new density mesh. The use the proper outline to create your final mesh.

I hope it helps,
Costas

Hi,
if i choose the 'resample outline' the mesh will be in a uniform density and if i use calculator option also the mesh will be uniform but dense. I need a mesh density depends on the bathimetric data. But if i don't choose 'resample outline' mesh looks denser in small depth area and increasing gradually to larger depth (attached mesh 01 & 02 files)

I created one more offshore boundary but the meshes not creating upto that. do i need to replace the old boundary by the extended boundary? Sorry i really don't know how to add nodes in the offshore boundary. Do i need to use the element split option or any other option in T3 mesh tool?

-regards,
smk.svks

Hi,

I use an external drawing tool (AutoCAD Civil3D) to create the outline and insert nodes and then import it to BlueKenue so I can't help you with these details.

Maybe this post will be of some help:
Creating a mesh with fixed outline geometry

If you have created the new 'extended' outline for the density mesh, you have to add it again in the Outline field of the T3 Mesh Generator. It will not seem to make a difference but it will replace the existing one. If you are not sure, create a new T3 Mesh Generator object and do it from scratch.

Costas

Dear BlueKenue users,

I would like to ask if there is an alternative way to refine a mesh. Until now, I found out that way, which is similar to the tutorial:

-1*A+number (e.g. = 1), where A = the depth

In this way, more refined mesh is obtained for shallower parts.
I would like to ask if someone knows a way to refine depending on the slope of bathymetry (i.e to get a finer mesh at areas where the depth varies quickly, larger slopes).
Or, a way that relates the maximum triangle area A to depth h via a user-defined constant alpha, as follows:

h/A ≥ alpha

I would like to thank you for your time.

Kind regards,

Apostolos

Dear Apostolos,

You can use surface slope as a density parameter, in a similar way bottom elevation is used in the tutorial above. All you have to do first is to create a mesh that has average slopes stored in each node. You can do that easily with BK. Select your bottom elevation mesh and then go to Tools->Extract Surface->Slopes.

Regarding your second question, I believe that the density function in BK relates to the element edge length, not the area. However, if we assume the triangles/elements is equilateral, then element area is equal to (element side)^2*sqrt(3)/4. You can use this formula to depend density on area instead.

Regards,
Costas

Dear Blue Kenue users,

I would like to ask about an issue I am frequently faced with.
When I create a depth-dependent refined mesh, curved holes are generated at the boundaries. Consequently, the created mesh is problematic.
Did anyone had the same problem and if yes, did you manage to solve it?

Kind regards,

Apostolos

Hi Apostolos,

This normally occurs when conflicting criteria are passed to the mesher resulting in VERY thin edge elements. The subsequent laplacian smoothing step then pulls these thin elements into the interior. If you turn off the "Auto Smooth Mesh" option the "curved holes" will disappear but you will have bad elements on the edge of your domain.

Please post your t3m file here so we can diagnose the problem.

Cheers... Martin

Dear Martin, thank you very much for your reply.

I post the t3s file and the t3m file.

Kind regards,

Apostolos

please find the files

Dear Apostolos,

I have found that if you use the same mesh for density, the function does not work as expected.

In order for the density function to work, it seems that the 'density mesh' should extend some distance outside the 'final mesh'. What I do usually is offset my boundary line by 50m or so and create a new, greater mesh dedicated for providing the 'density' function.

Maybe this is your case also.

Costas