Elucidating the importance of sediment avalanches in scour at obstacles

Soto, Jorge; Link, Oscar; Brevis, Wernher

Abstract

An experimental analysis of the dynamics of avalanches for different stages of development and turbulent flow conditions is introduced. Experiments were conducted in a laboratory flume using clear-water conditions and a video camera placed within an acrylic cylinder. The results of a proper orthogonal decomposition of the pre-processed image sequences highlighted the existence of two types of sand avalanches: Type I corresponding to a narrow and vertically long-advancing slide, and Type II characterized by an elongated and short-advancing pattern. Temporally speaking, sand avalanches were triggered aperiodically, resembling the behaviour of the horseshoe vortex system. The frequency of occurrence of avalanches decreased with time, while the estimated volume of mobilized sand increased in the same period. The sand slide magnitudes and associated inter-avalanche time were Log-Pearson 3 distributed. Sand avalanches are an important scour mechanism, which depending on the flow intensity contribute to about 40% to 60% of the scoured volume.

Más información

Título según WOS: Elucidating the importance of sediment avalanches in scour at obstacles
Título de la Revista: JOURNAL OF HYDRAULIC RESEARCH
Volumen: 60
Número: 1
Editorial: TAYLOR & FRANCIS LTD
Fecha de publicación: 2022
Página de inicio: 62
Página final: 73
DOI:

10.1080/00221686.2020.1866694

Notas: ISI