Two-Dimensional Numerical Modeling of Flow in Physical Models of Rock Vane and Bendway Weir Configurations

Drew Baird,S. Scurlock,Steven Abt,Benjamin Abban,Christopher Thornton

doi:10.3390/w13040458

Abstract

While there are a wide range of design recommendations for using rock vanes and bendway weirs as streambank protection measures, no comprehensive, standard approach is currently available for design engineers to evaluate their hydraulic performance before construction. This study investigates using 2D numerical modeling as an option for predicting the hydraulic performance of rock vane and bendway weir structure designs for streambank protection. We used the Sedimentation and River Hydraulics (SRH)-2D depth-averaged numerical model to simulate flows around rock vane and bendway weir installations that were previously examined as part of a physical model study and that had water surface elevation and velocity observations. Overall, SRH-2D predicted the same general flow patterns as the physical model, but over- and underpredicted the flow velocity in some areas. These over- and underpredictions could be primarily attributed to the assumption of negligible vertical velocities. Nonetheless, the point differences between the predicted and observed velocities generally ranged from 15 to 25%, with some exceptions. The results showed that 2D numerical models could provide adequate insight into the hydraulic performance of rock vanes and bendway weirs. Accordingly, design guidance and implications of the study results are presented for design engineers.

Highlights

Meandering river channels are complex and dynamic systems with planimetric flow path variability confined by the valley floor or meander belt width
This paper describes the physical model, which provided measurements from baseline and three rock vane and four bendway weir configurations
Sedimentation and River Hydraulics (SRH)-2D predicted less variability in the lateral velocity area, which continues until the wide section near model outlet

Summary

Introduction

Meandering river channels are complex and dynamic systems with planimetric flow path variability confined by the valley floor or meander belt width. Bank erosion due to lateral migration of meandering channels can encroach upon infrastructure. Engineers and scientists have developed methodologies to inhibit outer bank erosion to combat deleterious channel bend migration. Flow redirecting approaches, such as transverse instream structures, are used for stream bank protection rather than riprap revetments because these structures cost less and have more habitat benefits. These structures do not directly increase bank erosion resistance but rather alter flow patterns along the bank, thereby indirectly reducing applied flow shear stress

Methods

Results

Conclusion