Breakline in a 2d area and computation

[Anonymous]

Hello guys,
I am having a basin with 2 main reaches. I want to simulate a flooding event with different approaches. One approach is to create a 2d mesh for the whole basin with a cell size of 30mx30m and increased detail along the reaches by inserting breaklines at the centerlines. If i only had my 30x30m cell size mesh and i insert 10secs of computational interval, will i have to readjust this value after inserting the breaklines? Maybe because of the increased information at those points? (smaller value?).

Thank you in advance
Paul

[Anonymous]

Basically the question should also include if it is correct to insert a breakline at the centerline of a stream in order to increase the detail of a computational mesh.

[Anonymous]

Your computational time step doesnt necessarily have to change after a mesh is adjusted or further defined but that all depends on the final result.

IMO i do not think a stream centerline should be a breakline but rather the streams channel banks.

[Anonymous]

Correct.

Thank you Luis

[cameron]

You could use a stream centerline as a breakline or banks as breaklines. It all depends on the river, how wide it is, and your cell size.

[Anonymous]

That’s right. In my case the rivers are approximately 7 to 16 meters wide. I ‘ve set a 30x30m grid and up to 10m cells at the rivers. I think i’ll go with the stream centerline.

[robdir]

Look at pag.4.3-4.5 (Chapter 4 of 2D Modeling User’s Manual)…
Your Computation Interval should respect the Courant number (as described at pag.4.5).
If you insert breaklines along the main stream or banks you couldn’t ignore it.

[Anonymous]

Yes. Practically the best case would be to compute the Courant number for the maximum velocity assumed for your 2d cells.

[Author]

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