User Forum of Software BASEMENT

Alyssa

User

From: Aix-en-Provence, France

Registered: 2019-10-28

Posts: 41

Downstream boundary only fixed bed?

Hi

Is the downstream boundary always a fixed bed? It is not possible to have the bed free to move in this point?
This brings a big setback for long term simulations.
It means with aggradation the slope change is determined by this fixed point. Basically my slope should not change, and the bed needs to aggradate (or erode) parallel to the original bed.
Would this be not possible with Basement?
I'm trying in 1D, but I assume it is the same in 2D?

Thanks!

Alyssa

Matteo Facchini

Developer

From: Trento

Registered: 2014-09-05

Posts: 284

Re: Downstream boundary only fixed bed?

Hi Alyssa,

yes, as it is stated in the block-structure html page (help -> input block structure), IODown "is the only downstream boundary condition available for sediment transport at the moment. It corresponds to the definition of IOup. All sediment entering the last computational cell will leave the cell over the downstream boundary. Consequently, the bed-level should not change at the boundary."

To achieve what you are aiming at, I suggest you to use an "artificial" downstream channel and refer your results to the length you need. For example, if your channel is 10 km long, make it e.g. 15 km long and consider the first 10 km for your results.

Best
Matteo