|
|
When displaying EGL lines in the long section view, EGL is frequently shown to increase across manholes in the downstream direction (and direction of flow). This should not occur as (excluding pumps) if energy was really is higher on the downstream side the flow would be upstream?
The problem is most acute when using the 'max' button, presumably due to the velocity head being calculated using a very high velocity caused by instabilities. However it frequently appears in long sections taken at a particular time step too.
This issue has caused some engineers that I work with to lose confidence in ICM outputs and ICM in general. The work around it to just not show the EGL but that isn't ideal as EGL is useful to display.
InfoWorks ICM solves for mass and momentum (not energy) using the Saint-Venant equations. The EGL shown in the model is primarily for reference and visualization, not a direct output of an energy equation solution. It helps users interpret results in the context of traditional hydraulic analysis but should not be viewed as a rigorously computed energy profile