TUFLOW 2D Hydraulic Structures: Difference between revisions
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== What is the difference between downstream and upstream controlled flow? ==
Downstream control means a change in downstream water level will cause a change in upstream water level. Upstream control means the upstream water level is insensitive to the downstream water level and usually indicates the occurrence of supercritical flow.<br>
== What FLC values should be used for 2d_bg bridge if hB/T is below 2 or above 6? ==
Unfortunately, we have no data beyond the ends.
* hB/T ratios of less than 2 represent a very unusual bridge sitting low to the ground, and the peak FLC may increase above the end value (FLC of 0.42) in a way that doesn't follow the research trend or extrapolation. For these cases we would recommend using CFD modelling to obtain a more informed value. Alternatively, computing an FLC based on pressure flow might be considered.
* For hB/T ratios of greater than 6, the FLC is likely to continue to decrease, but probably not significantly. Clamping to the end value (FLC of 0.20) might be considered the more conservative approach (if the primary concern is flood levels upstream of the bridge).
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