An investigation of the energy dissipated in a surface roller

Summary

This paper deals with the problem of the dissipation of energy in hydraulic jumps, which is of importance in connection with the flow phenomena along weirs, sluice-gates etc. In fig. 2 the rough dimensions of the flow region investigated have been indicated. After measuring velocities and pressures in three cross sections, a net of average flow lines and orthogonal trajectories could be plotted (fig. 7) from which we calculated approximate values of the turbulent friction τ_ns at different levels (figs. 9 and 10), making use of equation (5). The amount of energy, converted into heat per cm³ and per sec, then could be calculated with the aid of equation (3), the result being shown in figs. 11 and 12. Due to errors in measurement, to the approximate nature of the calculations and to three-dimensional currents, discrepancies in the total amount of energy were found of −7.8 and −19.3% respectively.

The results probably can be made to apply to other cases of similar flow, such as eddies and wakes.