Numerical Study of the Hydrodynamics of Waves and Currents and Their Effects in Pier Scouring

Matias Quezada,Yarko Niño,Aldo Tamburrino

doi:10.3390/w11112256

Abstract

The scour around cylindrical piles due to codirectional and opposite waves and currents is studied with Reynolds Averaged Navier–Stokes (RANS) equations via REEF3D numeric modeling. First, a calibration process was made through a comparison with the experimental data available in the literature. Subsequently, not only the hydrodynamics, but also the expected scour for a set of scenarios, which were defined by the relative velocity of the current ( U C W ), were studied numerically. The results obtained show that the hydrodynamics around the pile for codirectional or opposite waves and currents not have significant differences when analyzed in terms of their velocities, vorticities and mean shear stresses, since the currents proved to be more relevant compared to the net flow. The equilibrium scour, estimated by the extrapolation of the numerical data with the equation by Sheppard, enabled us to estimate values close to those described in the literature. From this extrapolation, it was verified that the dimensionless scour would be less when the waves and currents are from opposite directions. The U C W parameter is an indicator used to adequately measure the interactions between the currents and waves under conditions of codirectional flow. Nevertheless, it is recommended to modify this parameter for currents and waves in opposite directions, and an equation is proposed for this case.

Highlights

The hydrodynamics of the coastal environment usually correspond to the result of the interaction of several force, such as waves, tides, and winds, that act at different spatial and temporal scales, thereby modulating circulation
A comparison of the results obtained numerically in this research with experimental data from other authors, show that computational fluid dynamic (CFD) REEF3D adequately models a hydrodynamic field in a combined other authors, show that CFD REEF3D adequately models a hydrodynamic field in a combined domain of waves and currents, correctly depicting both the instantaneous water surface and velocities domain of waves and currents, correctly depicting both the instantaneous water surface and developed by the flow of a freestream and the flow in the presence of a pile
The average hydrodynamics determined for each of the simulated scenarios showed that in 6 (E01 to E06) out of 8 cases, currents were the main flow mechanism over the waves, despite the relative velocity of current (U ) proposed by Sumer and Fredsøe [26], which indicate a combined flow regime. This was clearly reflected in the velocity profiles traced in points P1 to P8, where it could be verified that codirectional and opposite flow cases converge to the same vertical distributions of

Summary

Introduction

The hydrodynamics of the coastal environment usually correspond to the result of the interaction of several force, such as waves, tides, and winds, that act at different spatial and temporal scales, thereby modulating circulation. The convergence of coastal and fluvial environments is known as an estuary zone, and the resulting currents correspond to a complex interaction between tides, waves, winds, and river flow. In the case of waves orthogonal to currents, the experimental research developed by Feraci et al [4], Lim and Madsen [5] and Feraci et al [6] allows us to understand the effects of joint action on the The research developed by Umeyama [1,2,3], sought to analyze the behavior of Reynolds stress and velocity vertical distributions [1], the changes induced by the combined wave currents over the turbulent flow structures [2], and the surface elevation and particle velocities [3].

Objectives

Methods

Results

Discussion

Conclusion