Forces Induced on a Vertical Breakwater by Incident Oblique Waves

Abstract

Over the last years Navier-Stokes numerical models have been developed to accurately simulate wave interaction with all kinds of coastal structures, focusing on both functionality and stability of coastal structures. Although several models have been used to simulate wave interaction with coastal structures in two dimensions (2DV) there are a vast number of three-dimensional effects that need to be investigated in order to improve the design. In this paper a new model called IH-FOAM has been applied to study a vertical breakwater at prototype scale. As a first attempt of validation, the model has been used to simulate a regular wave train generated with a relative angle with the breakwater inducing three-dimensional wave patterns not only seaward the structure due to reflection but also generating an overtopping discharge variation along the breakwater trunk. Pressure laws and overtopping discharge at three different cross-sections along the structure have been studied. The pressure laws have been compared with classical Goda's formulation. Although, the numerical model predictions are in accordance with Goda's calculations, a clear three-dimensional variability of wave-induced pressure has been observed. Moreover, an additional study has been performed calculating pressure laws on the side-wall at the breakwater head. Large three-dimensional effects are detected from the simulations due to the flow separation at that area. Overtopping model predictions have been compared with Overtopping Manual calculations showing very close values along the trunk. However, lower overtopping discharge values are observed at the breakwater head. This paper is a preliminary work to show the range of applicability of a three-dimensional Navier-Stokes model to study wave interaction with a vertical breakwater under the action of an oblique wave train.

Simulation of Extreme Events of Oblique Wave Interaction With Porous Breakwater Structures

“…there is a spatial variation. This was shown in Lara et al (2012b) for the forces on a vertical impermeable breakwater exposed to oblique waves. In the present work the spatial variation was not addressed although it is expected that the reduction of the horizontal impact forces as found in the present simulations may also show some variation along the length of the breakwater.…”

“…Together with the wave generation capabilities presented in Jacobsen et al (2012) the OpenFoam model has contributed to the availability of open source CFD for coastal engineering topics. Examples of the use of OpenFoam for considering both flow in connection with breakwaters, modelling of scour around structures, and cross-shore morphodynamics were recently seen in for example Lara et al (2012b), Matsumoto et al (2012), Stahlmann and Schlurmann (2012), Jacobsen and Fredsøe (2014), and Higuera et al (2014b).…”

“…The short reproductions of extreme events were applied for investigating the effect of oblique waves on the forces on a breakwater sea-wall. Previously a numerical investigation of the effect of oblique waves on a vertical impermeable breakwater was presented in Lara et al (2012b) however this included regular waves. The effect of extreme events due to the interaction of the irregular waves was not investigated.…”

Modelling the Wave Overtopping Flow over the Crest and the Landward Slope of Grass-Covered Flood Defences

“…The modelled hydraulic forces included the maximum flow velocity, shear stress, normal stress and pressure. The pressures on hard structures during wave overtopping were simulated in other numerical studies to determine the forces on breakwaters [16,18] or sea walls [20]. The forces were calculated from the integration of the pressure over the impact duration and focussed on structural failure, which meant that the normal and shear stress were not determined in these studies.…”

“…Computational fluid dynamics (CFD) models can resolve these hydraulic variables and are an efficient tool to obtain insights into the wave overtopping flow. Recent numerical models for wave overtopping are focused on the waterside of flood defences to determine the structural response of breakwaters [16][17][18], the wave impact on vertical walls [19,20] or the amount of wave overtopping [21,22]. These numerical models solve different equations and methods to simulate the flow: the momentum equations using the smoothed particle hydrodynamics method [17,19], the non-linear shallow water equations in 2D without a turbulence model [21,22] and the Reynolds-averaged Navier-Stokes (RANS) equations using the volume of fluid method in 2D [18,20,21] or 3D [16].…”