Hot start for 1D/2D model

[Danny Burkett]

I have a 1D model connected to the upstream section of a 2D area and need to create a start up file for the model as I understand I need to have the 2D area wet otherwise it will crash. I have a fall of 10m or so fall from the 1D cross section to the outlet of the 2D area. I have tried a staged hydrograph for the 2D area and no flow in the 1D sections but the 1D sections are unstable. When I review the ‘startup’ results, the lower sections of the 2D model still have a ‘too’ high water level (3m above ground level) and I am not comfortable that my start up file is correct. If I end up using this start up file for my actual design flood run, the 1D sections are being reported as unstable.

My question is how do I set up the hot start file and have confidence that it is correct (i.e., the 2D area is wet but not 3m above the ground level).

[Anonymous]

You don’t need a hotstart file to run a 1D/2D connected model. A hotstart file might save you time for future runs because the computations start quicker.

The description is a bit hard to follow.

“I have a fall of 10m or so fall from the 1D cross section to the outlet of the 2D area”

Do you mean to the Inlet of the 2D area? If the 1D is 10 meters higher than the 2D and the 2D water surface is only supposed to be 3m or less, then that doesn’t sound like it is going to work.

[cameron]

Have you tried a initial conditions ramp up? The 1D model is the area that needs to be wet, 2D areas can be dry unless a cross-section is connected directly to the 2D area then you need have a continual flow of water from the 1D model to the 2D or the model will crash.

[Anonymous]

Jarvus,

Sorry for the confusion. There are two 1D cross sections, the first of which is above (i.e., outside) the 2D area and the second has an invert level of about 6.5m AHD and is connected directly to the 2D area. The downstream boundary condition for the 2D area has an invert level of about 2.5m AHD (approximately 1000m away) so there is at least a 4m fall across the 2D area.

[bora]

Hi

What is the best way to connect the below 2d areas with each other and 1d. I have 3 “2d areas ” and a 1d corss section.

I connected the ones at the left and right hand side using lateral structure. However, how do i connect the one called “deniz” with the left and right overbanks and the 1d cross section at the same time.

Thank you.

[Author]

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