6.3. The flow over a chain of V-shaped sharp crested weirs
The results of the studies on the flow over a chain of V-shaped sharp crested weir were transformed into dimensionless values. Equation (26) was used as a scaling factor for velocities. In these studies, the opening angle was β = 120°. For scaling discharges, Eq. 20 was applied.
All the dimensionless velocity profiles for flows in a pool-and-weir fishway with a V-shaped crest are plotted into the same graph (Fig. 25). It can be seen that velocities are lower near the bottom of the opening for higher dimensionless discharges. As the dimensionless discharge decreases, velocity distribution at the middle of the weir becomes more even, and finally, with the smallest dimensionless discharges, velocities at the bottom are higher than at the surface.
Figure 26. Dimensionless velocities v* at the V-shaped sharp-crested weir of a pool-and-weir fishway with different pool lengths L and dimensionless discharges Q*.
Velocities at the mid-axis of the cross section are approximately one, which means that they are nearly the same as the mean velocity of the cross-section. The highest velocities are near the surface and the lowest are near the bottom of the opening.