Three-Dimensional Numerical Modeling of Pier Scour Under Current and Waves Using Level-Set Method

Abstract

A three-dimensional (3D) computational fluid dynamics (CFD) model is used to calculate the scour and the deposition pattern around a pier for two different boundary conditions: constant discharge and regular waves. The CFD model solves Reynolds-Averaged Navier–Stokes (RANS) equations in all three dimensions. The location of the free-surface is represented using the level-set method (LSM), which calculates the complex motion of the free-surface in a very realistic manner. For the implementation of waves, the CFD code is used as a numerical wave tank. For the geometric representation of the moveable sediment bed, the LSM is used. The numerical results for the local scour prediction are compared with physical experiments. The decoupling of the hydrodynamic and the morphodynamic time step is tested and found to be a reasonable assumption. For the two situations of local pier scour under current and wave conditions, the numerical model predicts the general evolution (geometry, location, and maximum scour depth) and time development of the scour hole accurately.

Experimental Study of Local Scour around Tripod Foundation in Combined Collinear Waves-Current Conditions

“…When KC was fixed, the equilibrium scour depth increased with increasing U cw , and the equilibrium scour depth approached an asymptotic value corresponding to the case of current-only when U cw ≥ 0.7, indicating the scour process was dominated by current. Afzal et al [20] adopted the open-source CFD model REEF3D to study the scour evolution and hydrodynamics around a pier in waves and current, and the calculating results correspond well to the experimental data. Later, Quezada et al [21] used the REEF3D to investigate the scour morphology and scour process around a pier in combined waves and current.…”

Physical Modelling of Arctic Coastlines—Progress and Limitations

“…Close into the shoreline, shallow water wave equations help formulate coastal flows and tidal motions, and a combination of equations is, e.g., used to predict combined effects of waves and currents [45]. More sophisticated numerical models, solving for the Navier-Stokes equations, can be employed where smaller time and length scales prevail [71,72], or localized structure-flow interactions (e.g., scouring) occurs [73]. Often, studies on coastal erosion are also supplemented by experimental [46], or analytical-statistical [42,43] means used to inform numerical modeling or vice versa.…”

Scour around Piers under Waves: Current Status of Research and Its Future Prospect

“…where ϕ is the bias, N s is the sediment number, R ed is the grain Reynolds number based for the bed grain diameter, d, and D r is the relative density. Afzal et al [39] introduced a 3D numerical model to calculate the scour depth and the sediment deposition around a cylindrical pier, using the level set method. It may be noted that the 3D numerical model is used to provide insight into the scour mechanism.…”