Observations from Contraction–Scour Experiments Conducted with a Large Rectangular Channel
- 1 August 2021
- journal article
- research article
- Published by American Society of Civil Engineers (ASCE) in Journal of Hydraulic Engineering
- Vol. 147 (8), 04021025
- https://doi.org/10.1061/(asce)hy.1943-7900.0001903
Abstract
This paper presents observations on clear-water and live-bed contraction scour caused by subcritical flow along a large rectangular channel. Three contraction ratios (contraction width/approach–channel width) were used: 0.25, 0.50, and 0.75. Each ratio included a 45° transition linking the contraction to the approach channel. Contractions scour relates to three categories of contraction length: length shorter than flow-separation length at contraction entrance, length exceeds flow-separation length, and length is sufficiently long to develop uniform flow in contraction. Flow-choking was avoided. The experiments focused on the second category, herein termed intermediate-length contractions. Light detection and ranging (LiDAR) scans showed that maximum scour depths occurred at a flow vena contracta (formed within the contraction entrance), the entrance corners, and the contraction exit. The observed sour depth in the vena contracta exceeded the depths estimated using the existing HEC-18 equations for contraction-scour. The deepest scour occurred at entrance corners except for the smallest ratio, which produced a step scour.Keywords
This publication has 8 references indexed in Scilit:
- Optimal Configuration of Rock Vanes and Bendway Weirs for River Bends: Numerical-Model InsightsJournal of Hydraulic Engineering, 2021
- Scour Concerns for Short-Span Masonry Arch BridgesJournal of Hydraulic Engineering, 2020
- Scour in Long ContractionsJournal of Hydraulic Engineering, 2005
- Bed Erosion in Rectangular Long ContractionJournal of the Hydraulics Division, 1981
- Equilibrium Depth of Scour in Long ConstrictionsJournal of the Hydraulics Division, 1966
- An Analysis of Relief Bridge ScourJournal of the Hydraulics Division, 1963
- Scour at Bridge CrossingsJournal of the Hydraulics Division, 1960
- Effect of channel‐contraction works upon regimen of movable bed‐streamsEOS, Transactions American Geophysical Union, 1934