User Forum of Software BASEMENT

Deborah

User

Registered: 2020-03-21

Posts: 8

HQ-relation boundary

Hello,

I would like to reproduce a simulation with basement 3.0 that has been done with basement 2.8. The simulation consist of sediment transport in a large river.

As the output boundary, I set the hqrelation_out. I obtained different results from the basement 2.8 simulation. The flow speed is close to 0 and the water depth is very high for a river. I tried with uniform_out boundary and the results are quite similar.

Afterwards, I did severals simulation with differents HQ-relation-file and I obtained each time the same results.

I would prefer to use the HQ-relation-out boundary. However I really don't understand why I obtain unrealistic results. Can someone help with the problem ?

Thanks in advance,
Déborah

Matthias Bürgler

Developer

From: Zürich

Registered: 2019-04-04

Posts: 150

Re: HQ-relation boundary

Hi Déborah

What did you specify for the hq-relation boundary condition of the BASEMENT 2.8 simulation (slope or file)? If you used 'slope', then the closest boundary condition in Version 3.x is probably uniform_out. If you used 'file', the hq_relation is the closest boundary.
Did you specify the h in terms of absolute elevation?

Best regards
Matthias

Deborah

User

Registered: 2020-03-21

Posts: 8

Re: HQ-relation boundary

Hi Matthias,

I would like to use the file. In my H-Q relation file(see below), h is the water surface elevation. Do I need to specify h as the water depth ? 

HQ-relation file 
449.70    0
450.733    103
451.618    278
455.263    1404
456.162    1804

Déborah

Matthias Bürgler

Developer

From: Zürich

Registered: 2019-04-04

Posts: 150

Re: HQ-relation boundary

Hi Déborah

The H is specified as the water surface elevation, as you did correctly. Have you tried changing the upstream_direction of the outflow nodestring? If this is specified wrong, then there won't be any outflow. This is the only idea that i currently have for this problem.

Best regards
Matthias

Matthias

Advanced_User

Registered: 2014-12-16

Posts: 29

Re: HQ-relation boundary

Another input: Maybe the file was not read correctly?
You should use comma separated input-files
e.g.
449.70, 0
450.733, 103
....