Modifying a mesh

[mdjames 0]

Hi,

In SMS 10.1, given a 2-D mesh (extension *.2dm), can I back-track and add new features, such as an island? I'm trying to construct a new mesh for an FVCOM model run.

Thanks!

Matt

[cameronj 1]

There is no easy way to back track and start over without using the map module to generate the mesh in the first place. In your case you could either delete the elements manually from the mesh or convert the mesh to map and make adjustments from there and then regenerate the mesh. Depending on the amount of elements in your model, the second option could take a long time to convert to map and then back to mesh.

Cameron

[Alan K. Zundel 1]

Cameron is right that the easiest way is to use a conceptual model to create the mesh in the first place, and then just modify the conceptual model.

If you don't have a conceptual model, there are three general options:

1- Convert the mesh to a conceptual model by right clicking on it in the project explorer and converting. You can convert material zones and mesh boundaries to arcs. This won't guarantee that you get the exact same mesh, but it honors the regions.

2- Build a "piecewise conceptual model". This is done using the following steps:

a- convert the mesh to a scatter set if you need to save the original.

b- deleting a region of the mesh (both nodes and elements) creating a "hole" where you want to change the simulation.

c- creating a nodestring around the new "hole" and convert it to a new coverage. You can do anything you want inside that coverage as long as you don't redistribute the boundary that connects it to the old mesh.

d- do a "map -> 2d mesh", but don't delete the existing mesh.

3- Edit the mesh by hand. This is tedious and I wouldn't recomend it.

[amy 1]

Hi,

In my case, I am calibrating a model (ADCIRC) using a mesh, wich does not include a breakwater because I am using bathymetry, WSE and velocity data aquired before building the breakwater. Then, I want to use the calibrated model, with exactly the same mesh, except including modifications just to account the breakwater, for a later simulation. Is there other option than the 3rd one you mentioned? I am cheking your Lesson 4 "ADCIRC Mesh Editing and Parameters", however it seems not to work in my case, because the breakwater (island).

Thanks.

Amy

[Alan K. Zundel 1]

Amy,

I didn't see your query last month.

If I understand you correctly, you are trying to simply turn off the elements that cover the region where the breakwater is to be (or was) constructed). Is that correct?

Since ADCIRC does not support the option to turn elements off by material type, you could simply delete the elements. If there are nodes in the interior of the breakwater region, you would no longer be able to associate the solution from the preconstruction grid directly. To do this, do the following:

1- Load the calibrated, pre-breakwater grid and the solution for this grid.

2- Right click on the mesh and convert it to a scatter set.

3- Define a polygon that encloses the breakwater in an area property coverage in the map module.

4- Select this polygon, and use the "Select|Delete" command in the Feature object menu to select the elements that cover the breakwater (inside the polygon).

5- Delete the selected elements.

6- Delete disjoint nodes (these are inside the breakwater region).

7- Save a new copy of your grid that includes the breakwater.

8- In the scatter module, interpolate the pre-breakwater solution onto the new grid and save the project.

9- Run the modified mesh in ADCIRC, load the new solution, and compare.

I hope this helps.

Alan