User Forum of Software BASEMENT

PGB

User

From: Lisbon

Registered: 2020-04-10

Posts: 1

Simulation of outflow boundary restriction (canalized river)

Hello,

I want to simulate a flow restriction due to the presence of a canalized river section in the downstream boundary. The objective is analysed the flooding occurrences in the river. Since I did not find a boundary condition that allows to simulate a section restriction (pipe section), I used the hq relation. The maximum outflow flow is known. The simulated hydraulic behaviour in term of flooding occurrence looks acceptable.

However, the warning "A problem occurred with the outflow hq relation boundary. The outflow velocity exceeds 200 m/s " is appearing.

This warning appears until the output flow reaches the maximum flow value.

How can I solve this warning? Is there another outflow condition that allow to simulate the section restriction?

Best regards,

Paula

Matthias Bürgler

Developer

From: Zürich

Registered: 2019-04-04

Posts: 150

Re: Simulation of outflow boundary restriction (canalized river)

Hi Paula
I think hqrelation is the appropriate boundary for such a case. Otherwise have a look at the gate boundary condition.

Regarding the warning of velocity>200m/s: This can occur e.g. if you have steep elements along your boundary condition, small elements with small angles or elements with flow depths close to the minimum flow depth. First i would try different values for the minimum flow depth and see if it the warning disappears. Also have a look at your mesh for the first steep/small elements.

Best regards
Matthias