Description
A sluice gate is an underflow gate with a vertical sharp edge for stopping or regulating flow.
The specific energy concept can be applied to predict the flow under a sluice gate as a function of the gate operation. For a give gate opening, a specific discharge (q = Q/B) takes place and there is only one specific energy/flow depth curve (Chanson 2004). The upstream and downstream values of the specific energy are equal by application of the Bernoulli equation, neglecting headloss. For this value of specific energy, there are two possible values of the flow depth : one subcritical depth (i.e. upstream depth) and one supercritical depth (i.e. downstream depth). If the value of the specific energy is known, the upstream and downstream flow depths are deduced from the specific energy curve.
If the specific energy is not known a priori, the knowledge of the upstream flow depth and of the flow rate fixes the specific energy, and the downstream flow depth is deduced by graphical solution. If the discharge remains constant but for a larger gate opening, the upstream depth is smaller and the downstream flow depth is larger.
The video shows the underflow beneath a vertical sluice in a 0.25 m wide channel in the Gordon McKay Hydraulics Laboratory of the University of Queensland.
