Side-Channel Spillway Model

[Wicus du Plessis]

Hi,

I would appreciate your help on the following model.

I am trying to model a side channel spillway of a dam. As a first setup, I am trying to model just the side-wall as a lateral structure in a channel. The channel cross-sections start upstream of the lateral weir wall and ends at the dam wall.

The steady flow model struggles to converge. However, an unsteady flow model with the following boundary conditions manages to converge (but with issues I’ll discuss shortly) :

-US : Flow Hydrograph
-DS : Rating curve simulating a small weir section allowing a small % of flow to continue in the channel but 99% should go over the lateral structure.

My Problem :
The results indicate an increasing energy line (as seen on profile plot below), which is impossible right? Note that identical cross-sections were added downstream of the lateral structure as an attempt to stabilise the model. Any ideas what could cause this? I’m keen to provide more info as required, just ask.

The rest of the output seems fair.

Regards
Wicus

[yaseen wsu]

I also have a problem, how can I inlet the boundary condition for the side weir, I have the design discharge and maximum water level over spillway crest
regards

[Author]

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