Author(s): Ryugen Satoh; Masayuki Takahashi; Iwao Ohtsu

Linked Author(s): Ryugen Satoh, Masayuki Takahashi, Iwao Ohtsu

Keywords: Hydraulic jump; Turbulence; Jump length; Energy equation

Abstract: The classical hydraulic jump with a surface roller is a well-known phenomenon. For a supercritical flow below a sluice gate in a horizontal rectangular channel, a boundary layer develops from the section at the vena contracta and reaches the water surface at the critical point, after which the flow is developed. If the toe of the jump is located downstream of the critical point, this is called a jump with a fully developed inflow condition (FD jump). Subsequently, for a jump with an undeveloped inflow condition (UD jump), the jump toe is at the vena contracta section. For FD and UD jumps, it is necessary to clarify the jump length physically. The relation between the jump length and energy dissipation should be elucidated with the physical meaning based on the energy equation. This study shows the turbulence characteristics in FD and UD jumps under a given inflow Froude and Reynolds numbers. The distributions of the velocity and the turbulence intensity are demonstrated experimentally for FD and UD jumps. The relation between the jump length and the energy dissipation is elucidated by using the energy equation for the mean flow and the turbulence. The convection of the turbulent energy and the work performed by the Reynolds stresses are indirectly calculated, showing that the jump length can be interpreted as the length of the zone required to achieve the energy dissipation in the jump.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022832

Year: 2022