User Forum of Software BASEMENT

nicolagroff

User

Registered: 2017-08-07

Posts: 10

Mass balance problems with weir_out_constant Boundary Condition

Hi,

I tried to set up the initial condition for a simulation in a river, where the outflow boundary is a weir.
At the outflow boundary I put the weir_out_constant Boundary Condition, setting the Poleni factor and the weir elevation.
As inflow boundary I use a constant discharge and I set up an initial "dry" condition.

I tried to change the weir elevation and the minimum water depth, but the problem is still there.

When I start the simulation, I get a lot of MASS BALANCE PROBLEM: h = -5.51518 < 0.0

If I use another Boundary Condition, such as uniform_out or zero_gradient_out, I have no problems.

What could be the problem?

Thanks for your hep in advance

Nicola

Matteo Facchini

Developer

From: Trento

Registered: 2014-09-05

Posts: 281

Re: Mass balance problems with weir_out_constant Boundary Condition

Hi Nicola,
did you check the elements that are giving you troubles? You can do that by running basement in debug mode.
I guess there is something wrong in the way you set up your downstream boundary condition, but it is hard to say without checking ouy your input files.
Cheers
Matteo