Author(s): J. Hu; Y. Li; H. Chanson

Linked Author(s):

Keywords: Physical modelling; Sidewall baffle; Fish-friendly culvert; Hydrodynamics; Triple decomposition

Abstract: A near-full-scale physical modelling was performed on the oscillation and instability of open-channel flow in a fish-friendly culvert equipped with full-height sidewall baffles. High-resolution measurements of the instantaneous flow velocity were conducted using a Vectrino+ acoustic Doppler velocimeter (ADV). The physical results were marked by the existence of some low-frequency seiche phenomenon. A well-established triple decomposition technique was applied to the time series of free-surface and velocity time-series. The low-pass components confirmed a unique flow structure, consisting of a high-velocity zone in the main channel and a low-velocity flow reversal within the lateral cavities. The band-pass components corresponded to the low-frequency flow oscillations, highlighting the complicated transverse interactions between the lateral cavity and the main channel. The high-pass velocity components were related to the 'true' turbulence characteristics. The current study provides some further insights into the sustainable design of culverts to assist with upstream fish migration in man-made and natural fast waterways.

DOI: https://doi.org/10.26077/9f7b-59e2

Year: 2022