Hydrodynamic and morphologic investigating of the discrepancy in flow performance between inclined rectangular and oblong piers

Abstract

Accurate estimation of local scour is crucial for designers and stakeholders that involved in bridge pier construction. Understanding the scour mechanisms at different cross sections is essential. This study aims to re-evaluate how the inclined rectangular and oblong piers influence the local scour. The flow behaviour around two rectangular and oblong shaped piers with vertical and inclination angles (10⁰,21⁰ and 30⁰ downstream flow direction) under steady-current, shallow flow and clear water conditions was numerically investigated. To achieve this, a hydrodynamic coupled with morphological model are created and tested using experimental data sets on flow and scour. The reliability of flow velocity predictions was verified with high accuracy. The maximum scour depth around inclined rectangular and vertical oblong pier was reduced by 19 and 21% respectively compared with vertical rectangular pier. The simulation results reveal that although oblong piers play a significant impact in minimizing scour development in comparison to rectangular piers, inclined rectangular piers may experience significantly less scour. However inclined oblong piers, regardless of their round nose shape (low intensity of the downward flow), demonstrate a less reduction in eroding the bed around the pier compared to the vertical oblong piers.