make mesh density finer at certain area

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Seungjin Baek, modified 7 Years ago.

make mesh density finer at certain area

Youngling Posts: 3 Join Date: 8/29/17 Recent Posts

Dear all,

I couldn't find any tutorial or solution to make certain area of flexible mesh finer than everywhere else. For example, I would like to make the river and flood plain with finer mesh while keeping the remaining area with coarser triangles.

I tried everything I could on RGFGRID, but I don't seem to be able to fine the solution.

I first create mesh using polygon -> nicely uniform mesh is created.
Then I create another polygon in the middle, then tried mesh creation again, but from this point on, there are various error messages and outcome are different every time. Sometimes it creates mesh with holes with the polygon I just drew. Sometimes it creates a new mesh on top of the existing mesh - with nodes not connecting at all..

I'm frustrated and I find the Delft3D user guide to be extremely lacking many details.

Erik de Goede, modified 7 Years ago.

RE: make mesh density finer at certain area

Youngling Posts: 16 Join Date: 1/7/11 Recent Posts

Dear Seungjin Baek,

Did you try 'Refine Casulli'? See Section 5.3.12 of the RGFGRID User Manual. In this way, you can locally refine the grid.

Erik de Goede, Deltares

Seungjin Baek, modified 7 Years ago.

RE: make mesh density finer at certain area

Youngling Posts: 3 Join Date: 8/29/17 Recent Posts

Erik de Goede:

Dear Seungjin Baek,

Did you try 'Refine Casulli'? See Section 5.3.12 of the RGFGRID User Manual. In this way, you can locally refine the grid.

Erik de Goede, Deltares

This is what I got from using 'Refine Casulli'

1) first image - uniform density of mesh

2) second image - after I used 'Refine Casulli'
It creates weird cell configurations in the area wrapped by a polygon. I would like to have quadrilateral cells for the area I surrounded by the polygon which represents a channel.
Can it not be possible?

3) third image - as in the banner of this website up top. I would like to have a nice combination of quads for channel and triangles for floodplains..
This process is very easy with MIKE mesh generator, but RGFGRID seem to be hard to create this formation, or I must be missing something here.

Erik de Goede, modified 7 Years ago.

RE: make mesh density finer at certain area

Youngling Posts: 16 Join Date: 1/7/11 Recent Posts

Dear Seungjin Baek,

Indeed, this is what happens if "Refine Casulli" is applied. A cell is split in three parts: 25%, 50% and 25 %. This is what you see in your refined area. In a next step you have to orthogonalize the polygon ares. Then, it will look better;see the attachment.

Erik de Goede, Deltares