Abstract
This paper evaluates the results of two fundamentally different numerical models: DualSPHysics and SWASH, which can be used to assess the ability of coastal defense structures to offset or mitigate the water overtopping and subsequent implications for expected future sea level rise. The models are open source implementations of the smoothed particle hydrodynamics (SPH) method and of a non-hydrostatic adaptation of the non-linear shallow water (NLSW) equations, respectively. The small-scale physical experiment of Stansby and Feng (2004) is used to validate and asses the performance of the two numerical models for the case of breaking monochromatic waves overtopping a coastal dike. Numerical and experimental time-histories of water surface elevation are quantitatively compared and numerical velocity fields during the processes of wave breaking and overtopping are analysed in detail. In addition, to further validate the DualSPHysics model, numerical experiments are performed considering the more realistic case of irregular waves using the SWASH model as benchmark. Overall, results provided by both numerical models are generally comparable, although some strengths and shortcomings of each are highlighted. These results can provide guidance in selecting the most appropriate model for a particular situation given specific accuracy requirements and availability of resources.
Highlights
Climate change and the associated expected sea level rise will affect the performance of many existing coastal defence structures such as breakwaters, seawalls, and dikes, whose integrity under such changing conditions need to be reassessed
This paper evaluates and critically compares two fundamentally different numerical methods: the smoothed particle hydrodynamics (SPH) method and a non-hydrostatic adaptation of the non-linear shallow water (NLSW) equations with the goal of assessing their relative suitability for evaluating the implications of sea level rise and wave interaction with coastal structures
For the case of monochromatic waves, quantitative comparison of the numerical results with physical measurements of water surface elevation along the foreshore indicates that both models simulate correctly the magnitude and rate of reduction in wave height and energy dissipation associated with the wave breaking process
Summary
Climate change and the associated expected sea level rise will affect the performance of many existing coastal defence structures such as breakwaters, seawalls, and dikes, whose integrity under such changing conditions need to be reassessed. Design guidance for soft alternatives is generally scarce, compared to more conventional structures, and numerical modeling appears to be a promising approach to overcome this gap. This paper evaluates and critically compares two fundamentally different numerical methods: the smoothed particle hydrodynamics (SPH) method and a non-hydrostatic adaptation of the non-linear shallow water (NLSW) equations with the goal of assessing their relative suitability for evaluating the implications of sea level rise and wave interaction with coastal structures. The SPH method was first considered in 1994 to simulate general free-surface flows (Monaghan, 1994) by solving the full compressible Navier-Stokes equations. With the general exception of Didier and Neves (2009, 2010), the method has rarely been applied to wave-structure interaction scenarios in which a wide array of non-linear processes including wave propagation and transformation, breaking, run-up, and overtopping take place. Validation of the SPH method for practical purposes is still scarce, especially for the case of irregular waves
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