Characteristics of turbulent flow around bridge abutments in the presence of vegetation in channel bed under ice-covered flow conditions

Abstract

During winter, ice cover frequently forms on the water surface of rivers with vegetated channel beds in cold regions. The investigation of the impacts of both ice cover and channel bed vegetation on flow structures around bridge abutments is essential for engineers to gain a comprehensive understanding of the complex interactions occurring in such a situation. In the present study, the flow structure around a rectangular bridge abutment in the presence of vegetation under ice-covered conditions has been studied. Considering different vegetation densities by arranging vegetation elements in square and staggered configurations, this study incorporates the influence of ice covers with different roughness, namely smooth and rough ice cover. Key turbulence parameters, including turbulence intensity, Reynolds shear stress (RSS), and turbulent kinetic energy (TKE), are also examined based on laboratory experiments. Results show that the shape of velocity profiles for flow over a vegetated channel bed changes from an S-shaped curve under an open flow condition to a convex shape under ice-covered conditions. The effects of an ice cover and vegetation on the flow around the bridge abutment create unpredictable turbulence intensity patterns. Under a rough-covered flow condition, there appears a larger area with negative Reynolds shear stress (RSS) downstream of the abutment. Turbulent kinetic energy (TKE) under ice-covered conditions has substantially lower magnitudes than in open flow conditions.