Numerical modelling of subcritical flow downstream of a labyrinth weir

© 2020 IAHR International Symposium on Hydraulic Structures, ISHS 2020.All right reserved.Labyrinth spillways are non-linear weirs folded in plan-view to provide a longer total effective length of the crest for a given overall spillway width, and consequently allowing a higher discharge capacity compared with a straight overflow weir for the same width and upstream energy head. To date, most studies on labyrinth weir hydraulics have been experimental and focused on the discharge capacity as a function of geometric factors and hydraulic parameters, such as the crest shape and sidewall angle, and the energy head over the weir, respectively. In this study, numerical simulations of subcritical flow downstream of a labyrinth weir were conducted using the computational fluid dynamics software ANSYS CFX. The results were compared with experimental data previously acquired on a fairly large-scale flume, including a trapezoidal labyrinth weir with quarter-round crest profile and sidewall angle ¿ = 30º. In general, fairly good agreement was obtained on the main flow properties downstream of the weir, such as flow depths, bottom pressure heads and velocities sufficiently distant from the invert, except in the vicinity of the weir.